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1.
The effect of protein depletion in the pregnant rat on the polyunsaturated fatty acid incorporation into very low density
lipoproteins (VLDL) has been investigated. The apoprotein pattern of these particles was determined. In in vivo experiments
the amounts of serum and liver triacylglycerol were determined. VLDL were isolated and their apo C concentration calculated.
In in vitro experiments the radioactivity of [3H] leucine incorporated into VLDL apoproteins was measured. The results show that protein depletion during pregnancy promotes
a drastic increase in serum and liver triacylglycerol. The VLDL isolated from these animals show an increase in the triacylglycerol/protein
ratio and a decrease in their content of apo C. Meanwhile, a significant reduction in the [3H]leucine incorporation into apo C peptides by the perfused liver of protein depleted rats was detected. On the other hand,
protein deprivation did not affect labeled linoleic and arachidonic acid incorporation into triacylglycerol of the newly secreted
VLDL. Taking these results together, let us deduce that a defective VLDL is secreted by the liver of the protein depleted
pregnant rats. The abnormal composition of these particles may influence its normal metabolism through their effects on lipoprotein
lipase and this fact could affect the normal supply of polyunsaturated fatty acids to the fetus. 相似文献
2.
An important and unusual aspect of the high density lipoprotein (HDL) in the rat is its tendency to undergo marked alterations
in structure in response to physiological perturbations. In this study, the role of the surface lipids for maintenance of
HDL integrity were investigated. Hydrolysis by pancreatic phospholipase A2 of the phospholipids of rat HDL in the presence of the d>1.21 g/ml fraction of rat serum results in an increase in the particle
diameter and an uptake of apo-E and apo A-IV from the lipoprotein-free fraction; augmentation of the albumin concentration
in the incubation mixture intensified the observed changes, probably due to enhancement of the compositional changes brought
about by phospholipase treatment. Phospholipase A2 treatment of the d<1.21 g/ml fraction of rat serum produces only minor changes in the properties of the isolated HDL. These
data suggest that changes in apoprotein content reflect an uptake of A-IV and E by the rat HDL, rather than a net loss of
apo A-I. Likewise, titration of the action of pancreatic phospholipase A2 on HDL apoprotein composition showed that initially a modest increase in apo A-IV content occurred, but with more extensive
phospholipolysis there was a considerably greater increase in the apo-E content of the particle. The data suggest that hydrolysis
of phospholipids such as occurs physiologically through the action of lecithin: cholesterol acyl transferase and hepatic lipase
may alter the HDL structure independently from changes effected in the neutral lipid core. 相似文献
3.
Arne T. Høstmark Øystein Spydevold Einar Lystad Eva Kristensen Ida Goffeng Bay 《Lipids》1982,17(7):489-499
The effect of varying the dietary sunflower oil/sucrose (SO/SU) ratio on rat plasma lipid concentration and lipoprotein distribution
was studied. Four groups of 10 rats were fed for 4 weeks diets with varying SO/SU ratios. Lipoprotein components were then
estimated in whole plasma and after cumulative density ultracentrifugation. Whole plasma triacylglycerol (TG), total cholesterol
(TC) and free cholesterol (FC) decreased with increasing SO/SU ratio; the CE/FC ratio increased, because CE remained virtually
unaltered. Plasma TG-lowering was due to a decrease in VLDL and LDL-TG. Protein, CE and FC in d=1.063–1.100 g/ml (HDL2b) and d=1.100–1.125 g/ml (HDL2a) lipoproteins decreased upon increasing the SO/SU ratio. In contrast, in d=1.125–1.200 g/ml (HDL3) lipoproteins, there was a concomitant increase in these components. Although increasing the SO/SU ratio effected more protein
and CE transportation in HDL3 and less in HDL2, the total amount of these components in high density lipoproteins (d=1.063–1.200 g/ml) remained constant. Apo A-I and apo
C-III decreased in HDL2 but increased in HDL3 upon increasing the SO/SU ratio. Also, HDL2 apo E, and the apo C-II/apo C-III and small apo B/large apo B ratios in VLDL and LDL were lowered by increasing the SO/SU
ratio. The hepatic VLDL-TG output during isolated liver perfusion was lowest in rats fed the diet with the highest SO/SU ratio.
In perfusate, like in plasma, the VLDL and LDL apo C-II/apo C-III ratio, as well as the small apo B/large apo B ratio, decreased
upon increasing the dietary SO/SU ratio. The results indicate that there can be appreciable diet-dependent variations in plasma
HDL subgroup distribution in spite of unchanged total HDL levels. 相似文献
4.
Maria Luz Fernandez A. Karin Conde Laura R. Ruiz Carlos Montano John Ebner Donald J. McNamara 《Lipids》1995,30(7):619-626
To test the effects of exchanging dietary complex and simple carbohydrate for fat calories on lipoprotein metabolism, guinea
pigs were fed two different fat/carbohydrate ratios: 2.5∶58% (w/w) or 25∶29% (w/w) with either sucrose or starch as the carbohydrate
source. Animals fed high-fat had higher plasma low-density lipoprotein (LDL) and hepatic cholesterol concentrations than animals
fed low-fat diets (P<0.01). The cholesteryl ester content per particle was higher, and the number of triacylglycerol (TAG) molecules was lower
in very low density lipoprotein (VLDL) and LDL from animals fed high-fat diets. Intake of high-fat/sucrose resulted in higher
plasma LDL concentrations than intake of high-fat/starch, and animals fed low-fat/starch had the highest plasma TAG concentrations
associated with VLDL particles containing more TAG molecules, as well as a TAG-enriched LDL. The activity of plasma lecithin
cholesteryl:acyl transferase (LCAT) was highest in animals fed high-fat/sucrose, and heart lipoprotein lipase (LPL) activity
was higher in animals fed high-fat diets. Hepatic apoprotein B/E (apo B/E) receptor number (Bmax) was increased 21% with low-fat diets (P<0.01). These results suggest that the hypercholesterolemia induced by high-fat and by sucrose intake are associated with
a higher plasma LCAT activity which results in a cholesteryl ester-enriched VLDL which, by the action of LPL, might be more
readily converted to LDL through the delipidation cascade leading to downregulation of hepatic apo B/E receptors. The hypertriglyceridemia
associated with low-fat intake may result from increased production of VLDL TAG, which would explain the increased TAG content
and the higher TAG/CE ratio of VLDL from animals fed the low-fat/starch diet. 相似文献
5.
M. L. Kashyap L. S. Srivastava B. A. Hynd G. Perisutti D. W. Brady P. Gartside C. J. Glueck 《Lipids》1978,13(12):933-942
The purpose of these studies was (a) to examine the relationship between total plasma triglycerides (TG) and the amount of
apolipoprotein CII (apo CII) in triglyceride rich lipoproteins (TRL), and (b) to determine whether TRL could be enriched with
apo CII in vitro. In 13 patients with primary endogenous hypertriglyceridemia, (log10) total plasma TG correlated inversely with the amount of apo CII per unit very low density lipoprotein (VLDL) protein (r=−0.76;p<0.005)
and VLDL TG (r=−0.75; p<0.005). The potency of VLDL to activate milk lipoprotein lipase (LPL) in hydrolyzing triolein was
studied in vitro. LPL activator potency per unit VLDL protein or VLDL TG correlated inversely with (log10) total plasma TG (r=−0.86 and r=−0.76, respectively; p<0.005). LPL activator potency per nM VLDL apo CII also correlated
inversely with (log10) total plasma TG (r=−0.49; p<0.01). In seven patients with familial type V hyperlipoproteinemia, the average amount of apo
CII in TRL protein was subnormal (5.86±0.62% vs 10.0±0.51% in normal subjects). The higher the (log10) total plasma TG, the lower was the apo CII content in TRL protein (r=−0.93; p<0.01). To determine the factors governing
the distribution of apo CII between lipoproteins and whether TRL could be enriched with apo CII, five approaches were undertaken:
(a)125I apo CII was added to mixtures of VLDL and HDL. The amount of labelled apo CII in VLDL was proportional to the ratio of VLDL
to HDL. (b) TRL from four patients with familial type V hyperlipoproteinemia was incubated with high density lipoprotein (HDL)
from a normal subject. An increase in the TRL/HDL ratio was associated with transfer of apo CII from HDL to TRL and a reciprocal
transfer of non-apo CII protein from TRL to HDL. Net apo CII enrichment of TRL protein was possible below a HDL/TRL protein
ratio of ca. 6 under the experimental conditions. (c) A fixed amount of normal plasma feed of TRL was incubated with different
amounts of TRL from two patients with familial type V hyperlipoproteinemia. The amount of apo CII that transferred from normal
TRL free plasma to the patient’s TRL was proportional to the amount of TRL in the mixture. (d) A doubling and tripling in
the amount of apo CII in TRL was found when apo CII was added directly to TRL from a normal subject and TRL from a patient
with familial type V hyperlipoproteinemia, respectively. (e) When apo CII was added directly to normal plasma and plasma from
a patient with primary type IV hyperlipoproteinemia, the peptide was taken up mainly by VLDL and HDL, indicating enrichment
of these fractions. The distribution of the added apo CII in each lipoprotein fraction resembled the distribution in the native
plasma. TRL was isolated after addition of apo CII to plasma from two patients with familial types IV and V, respectively.
Enrichment of TRL with apo CII was associated with an approximate 1.5-fold increase in the LPL activator potency per unit
TRL protein. These studies suggest that firstly, the amount of apo CII in TRL is inversely related to the severity of hypertriglyceridemia.
Secondly, the distribution of apo CII between TRL and HDL is governed by the mass ratios of these two lipoprotein classes.
Thirdly, plasma TRL and HDL have a reserve binding capacity of apo CII and fourthly, it is possible to enrich these lipoproteins
with this functionally important peptide. Whether net enrichment of TRL with apo CII and also an increase in its biological
activity to activate LPL in vitro is related to increased in vivo catabolic rate requires to be determined. 相似文献
6.
Studies investigated the effects of dietary fatty acid composition and saturation on the regulation of very low density lipoprotein
(VLDL) apo B flux, clearance, and conversion to low density lipoprotein (LDL) in guinea pigs fed semipurified diets containing
15% (w/w) corn oil (CO), lard (LA), or palm kernel oil (PK). Plasma cholesterol levels were highest with dietary PK (3.1±1.0
mmol/L) followed by LA (2.4±0.4 mmol/L) and CO (1.6±0.4 mmol/L) intake. VLDL particles were larger (P<0.05) in the LA (78±7 nm) and PK (69±10 nm) groups compared to animals fed CO (49±5 nm). VLDL-apo B fractional catabolic
rates (FCR) were highest in guinea pigs fed the LA diet (P<0.05) and VLDL apo B flux, estimated from VLDL 125I-apo B turnover kinetics, were higher in LA compared to PK or CO fed guinea pigs. In the case of PK consumption, the kinetic
estimates of VLDL apo B flux significantly underestimated rates compared to direct VLDL apo B secretion measurements and LDL
turnover analyses. These data demonstrate that differences in the composition and amount of saturated fatty acids have differential
effects on VLDL apo B flux, catabolism, and conversion to LDL which, together with changes in LDL receptor-mediated catabolism,
determine plasma LDL cholesterol levels in guinea pigs. The data also indicate that kinetic analysis of VLDL metabolism in
PK fed animals is inaccurate possibly due to the presence of a small, nonequilibrating pool of newly synthesized VLDL which
is rapidly converted to LDL. 相似文献
7.
Stearic acid as compared to myristate, palmitate, or oleate is poorly incorporated into triacylglycerol, a major lipid component
of very low density lipoprotein (VLDL). The present study investigated the effects of these fatty acids on VLDL metabolism
in cultured rat hepatocytes. All fatty acids stimulated [2-3H] glycerol incorporation into VLDL lipids and secretion of [3H]-labeled VLDL by hepatocytes. However, the rate of [3H]-labeled VLDL secretion in the presence of nonlabeled stearate (12.8±0.7 pmol/mg protein/4h) was 46, 59, and 22% of that
observed for those treated with myristate, palmitate, and oleate, respectively. [1-14C]Stearate as a substrate was also less effective than other labeled fatty acids to be incorporated into VLDL lipids. Of total
VLDL lipids synthesized from [1-14C] stearate, triacylglycerol accounted for 78% as compared to 88–97% of that derived from palmitate, myristate, and oleate.
The amounts of apoB100 and apoB48 were the same in hepatocytes treated with or without exogenous fatty acids. Similarly, the
rate of apoB synthesis from [35S] methionine was not affected by exogenous fatty acids. The treatment of cells with various saturated fatty acids increased
the particle size of VLDL to different extents. The largest particles of VLDL, with a mean diameter of 79.3±11.9 nm, were
seen in the cells treated with stearate, followed by those treated with palmitate and myristate (45.5±9.8 and 38.6±6.8 nm,
diameter, respectively). Clearly, hepatocytes treated with stearate secrete less VLDL and produce larger VLDL particles than
those treated with shorter-chain saturated fatty acids. 相似文献
8.
Catanozi S Rocha JC Passarelli M Mesquita CH Suguiama VY Guzzo ML dos Santos Filho A Quintão EC Nakandakare ER 《Lipids》2006,41(7):663-668
Dyslipoproteinemia of the Nagase analbuminemic rat (NAR) is characterized by elevated concentrations of VLDL and LDL attributed
to increased rates of liver lipoprotein synthesis. Increased lysophosphatidylcholine (LPC) in NAR HDL has been attributed
to high plasma LCAT activity. We show here that, as compared with Sprague-Dawley rats (SDR), NAR plasma triacylglycerol (TAG),
total cholesterol (TC), HDL TAG, protein, total phospholipids (PL), LPC, and PS are increased. These alterations rendered
the NAR HDL particle more susceptible to the activity of the enzyme hepatic lipoprotein lipase (HL), which otherwise was unaltered
in our study. Fractional catabolic rates in blood of the autologous 125I-apoHDL (median and lower quartile values), were, respectively, 0.231 and 1.645 (n=10) in NAR as compared with 0.140 and 0.109 (n=10) in SDR (P=0.012), corresponding to synthesis rates of HDL protein of 89.8±33.7 mg/d in NAR and 17.4±6.5 mg/d in SDR (P=0.0122). Furthermore, Swiss mouse macrophage free-cholesterol (FC) efflux rates, measured as the percent [14C]-cholesterol efflux/6 h, were 8.2±2.3 (n=9) in NAR HDL and 11.2±3.2 (n=10) in SDR HDL (P=0.03). Therefore, in NAR the modification of the HDL composition slows down the cell FC efflux rate, and together with the
increased rate of plasma HDL metabolism influences the reverse cholesterol transport system. 相似文献
9.
The fatty acid specificity of purified human milk lipoprotein lipase was studied using the C18 to C54 (total acyl carbon number) saturated and the C54 mono-, di- and triunsaturated monoacid triacylglycerols. Kinetic determinations indicated that the medium-chain triacylglycerols
were better substrates than long- or very short-chain saturated triacylglycerols. The unsaturated triacylglycerols were hydrolyzed
at rates comparable to that of tricaprylin with triolein having the highest rate of hydrolysis of the unsaturated species
tested. The enzyme attacked the primary ester bond much more readily than the secondary ester bond. The purified human milk
lipoprotein lipase showed a preferential stereospecific lipolysis of thesn-1-position of the triacylglycerol molecule. 相似文献
10.
Effect of chronic glucagon administration on lipoprotein composition in normally fed,fasted and cholesterol-fed rats 总被引:2,自引:0,他引:2
Catherine Guettet Najmuddin Rostaqui Denis Mathe Bernard Lecuyer Nicole Navarro Bernard Jacotot 《Lipids》1991,26(6):451-458
Male adult Wistar rats received daily (at 9 a.m. and 5 p.m.) 10 μg of zinc-protamine glucagon by subcutaneous injection for
8 days. Plasma cholesterol levels were decreased by 36% in fed rats, 33% in cholesterol-fed rats and by 55% in fasted rats.
Lipoproteins were separated into 22 fractions by ultracentrifugation using a density gradient. Glucagon administration decreased
the cholesterol content in all lipoproteins except low density lipoprotein (LDL1) (1.006–1.040) and very low density lipoprotein (VLDL) from cholesterol-fed rats. The main decrease (−57 to −81%) was observed
in 1.050–1.100 g/mL lipoproteins (LDL2 and HDL2), which contained a large amount of apo E, while HDL3 cholesterol was not affected. Triacylglycerol levels were decreased only in chylomicrons and VLDL (−70%) of fed and cholesterol-fed
rats, while plasma and lipoprotein triacylglycerol levels were not changed in fasted rats treated with glucagon. In normally
fed rats glucagon administration increased by 42% the fractional catabolic rate of [125I]HDL2 while the absolute catabolic rate appeared to be unchanged. Glucagon seems to be a potent hypolipidemic agent affecting mainly
the apo E-rich lipoproteins. Its chronic administration limits lipoprotein accumulation which occurs upon cholesterol feeding. 相似文献
11.
Gazi IF Apostolou FA Liberopoulos EN Filippatos TD Tellis CC Elisaf MS Tselepis AD 《Lipids》2011,46(10):953-960
The objective of the present study was to evaluate the effects of acute infection with Leptospira interrogans on lipids, lipoproteins and associated enzymes. Fasting serum levels of total cholesterol (TC), low-density lipoprotein cholesterol
(LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), apolipoproteins (apo) A-Ι, B, E, C-II, C-III and
lipoprotein (a) [Lp(a)] were determined in patients with Leptospirosis on diagnosis and 4 months after recovery as well as
in age- and sex-matched controls. Activities of cholesteryl-ester transfer protein (CETP) and lipoprotein-associated phospholipase
A2 (Lp-PLA2) as well as paraoxonase 1 (PON1) hydrolysing activity and levels of cytokines were determined. LDL subclass analysis was
performed with Lipoprint LDL System. Eleven patients (10 men, mean age 49.5 ± 8.4 years) and 11 controls were included. TC,
HDL-C, LDL-C, apoA-I, apoB and Lp(a) levels were lower at baseline, whereas TG and apoE levels were elevated compared with
4 months later. At baseline, higher levels of cytokines and cholesterol concentration of small dense LDL particles (sdLDL-C)
were noticed, whereas LDL particle size was lower compared with follow-up. Activities of plasma Lp-PLA2 and HDL-associated Lp-PLA2 were lower at baseline compared with post treatment values, whereas PON1 activity was similar at baseline and 4 months later.
4 months after recovery, the levels of all lipid parameters evaluated did not differ compared with controls, except for HDL-C
which remained lower. PON1 activity both at baseline and 4 months later was lower in patients compared with controls. Leptospirosis
is associated with atherogenic changes of lipids, lipoproteins and associated enzymes. 相似文献
12.
An acid lipase has been detected in bovine thyroid tissue using triolein as a substrate. The activity, probably associated
with the lysosomes, displays a rather broad pH-optimum in the pH 4 to pH 6.5 range. The lipase activity can be partially purified
by cosedimentation with lysosomes followed by solubilization through detergent and chromatography on Sephadex G-200 and carboxymethyl
cellulose. The elution profile on Sephadex G-200 shows one peak (moleculare weight 67,000±2,000). In the final CM-cellulose
step, two lipase peaks (lipase LA and lipase LB) are found. Sulhydryl reagents (iodoacetate, iodoacetamide, and N-ethylmaleimide) as well as mercuric ions markedly reduce
both enzyme activities. Calcium ions, EDTA, and heparin have no effect. Sodium fluoride and diisopropylfluorophosphate are
only slightly inhibitory. Sodium chloride causes a slight increase in both lipase activities. Anionic phospholipids such as
cardiolipin and phosphatidylserine are not essential for enzyme activity. 相似文献
13.
Assessment has been made of the specificity of a purified phospholipase A2 from the 106,000×g pellet (microsomal fraction) of bovine grey matter which shows strong activity toward phosphatidylinositol
(PI). In the first series of experiments involving the utilization as substrates of PI with different14C- or3H-labeled fatty acids in the 2-position, the purified phospholipase A2 most readily removed 16∶0 palmitic acid, followed by 18∶0 stearic acid, 18∶1 oleic acid and 20∶4 arachidonic acid. In the
second series of experiments, the purified phospholipase A2 showed preferential action toward PI (100%) compared to phosphatidylcholine (PC, 62.5%), phosphatidic acid (PA, 32.6%), phosphatidylethanolamine
(PE, 25.1%) and phosphatidylserine (PS, 21.5%), where each phosphoglyceride was labeled in the 2-position with [1-14C] oleic acid. In the third series of experiments, fatty acids were shown to cause inhibition of action of the purified phospholipase
A2 on 1-acyl, 2-[1-14C] oleoyl PI in the order 20∶4>18∶1>18∶0>16∶0 which is the reverse order to that just noted. In the final series of experiments,
the addition of the phosphoglycerides PC, PE, PS and PA in amounts of 5 or 10 μM caused either no inhibition (PE, 2%), slight
inhibition (PC, 15%) or reasonably significant inhibition (PA, 20% and PS, 40%) of action of the purified phospholipase A2 on 1-acyl, 2-[1-14C]-oleoyl PI. The pattern of specificity observed for the purified phospholipase A2 combined with its microsomal location are the expected properties of a phospholipase A2 that might function in a deacylation-reacylation cycle for modifying the fatty acid distribution in PI. 相似文献
14.
Nicotine, a major component of cigarette smoke, plays an important role in the development of cardiovascular disease and lung
cancer in smokers. The effect of nicotine on lipoprotein metabolism was studied using rats as the experimental animal. There
was a significant increase in the total cholesterol, phospholipids, and triglycerides as well as the amount of lipids associated
with very low density lipoprotein (VLDL) and low density lipoprotein (LDL) in sera of nicotine-treated rats. The incorporation
of 3H labeled leucine into the apo B was found to be increased both in the medium and associated cells in the hepatocytes isolated
from nicotine-treated rats indicating an increased synthesis and secretion of the apo B containing lipoproteins. This was
further confirmed by the higher incorporation of 14C acetate into total and individual lipids of LDL and VLDL secreted into the medium as well as that associated with different
lipids in the cell layer. The activity of lipoprotein lipase in extrahepatic tissues and plasma lecithin cholesterol acyltransferase
activity were significantly lower in nicotine-treated rats. These results indicate that nicotine exerts hyperlipidemic effects
particularly by increasing the synthesis and secretion of triglyceride-rich lipoproteins. Since nicotine is one of the major
hazardous components present in cigarette smoke and tobacco, one can extrapolate that the deleterious effect exerted by nicotine
on rats extends to cigarette smokers and those who use other forms of tobacco. 相似文献
15.
The catfish,Ictalurus punctatus, is an important model for studying the biochemical mechanisms of taste at the peripheral level. The type, amount and metabolic
activity of the lipids within this tissue play important roles in taste transduction by forming the matrix in which the receptors
for taste stimuli are imbedded and by acting as precursors to second messengers. The metabolic interconversions that occur
among the lipids on the taste organ (barbels) of this animal are reported here. When sodium [32P]phosphate was incubated with minced pieces of epithelium from the taste organ ofI. punctatus, phospholipids became labeled. Maximal incorporation occurred near 20 min for lysophosphatidylcholines (LPC),phosphatidylcholines (PC) and phosphatidylinositols (PI). The phosphatidylethanolamines (PE) and phosphatidylserines (PS) became labeled more
slowly. The label in LPC and PC declined from 20 min to 120 min, while that of the other fractions increased or was stable
over the 20–120 min time period. Upon addition of 1,2-di-[1′-14C]palmitoyl-sn-glycero-3-phosphocholine to the medium,14C was found within minutes in all of the phospholipids assayed. The amount of label incorporated increased with time, with
maximum labeling for all phospholipids occurring at 15 min. However,14C appeared predominantly first (by 5 min) in a neutral lipid fraction (fraction AG, consisting of free fatty acids, mono-
and diglycerides, triglycerides and methyl esters), then declined rapidly as the phospholipids gradually incorporated more
label. Within minutes of addition of 1-[1′-14C]palmitoyl-sn-glycero-3-phosphocholine (lysophosphatidylcholine) the14C-label was detected in the neutral lipid fraction AG, then in the PC fraction, and later in the other phospholipids. The
PC fraction was maximally labeled by 40 min.
Using the appropriate radiolabeled substrates, lysophosphatidylcholine phospholipase A1 and phosphatidylcholine phospholipase D activities were detected in this tissue. Very low activity of a phosphatidylcholine
phospholipase A2 was observed. The experiments indicate that there are active and rapid exchange, degradation, synthesis and scavenger pathways
of phospholipids in the taste organ of this animal, and suggest that phospholipases A1 and D-type activities are primarily responsible for the rapid breakdown of LPC and PC. 相似文献
16.
Hydrolytic Activity of Castor Bean Powder: Effect of Gum Arabic,Lipase and Oil Concentrations
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Florencia Salaberría Camila Palla María Elena Carrín 《Journal of the American Oil Chemists' Society》2017,94(5):741-745
Lipase activity from castor bean seed powders was evaluated in hydrolysis reactions at 37 °C. The effects of different concentrations of lipase powder (LP), substrate (high oleic sunflower oil, O) and surfactant (gum arabic, A) on lipase activity (R) were assessed using experimental designs. Considered variable bounds were: 0.05–0.15 gLP, 0.07–0.20 oil:aqueous phase (w/w) and 0–0.025 g gum arabic/mL. All variables had significant effects on the transformed response, R 1/2. The most important result was the negative effect of gum arabic in lipase activity, even when high oil concentrations were used. Experimental lipase activities involved in this work were within 0.32–16.90 mmolFFA/goil·gLP·h. Using 0.05 gLP and 0.20 oil:aqueous phase (w/w) without gum arabic, the activity of 20.47 ± 7.19 mmolFFA/goil·gLP·h was reached. 相似文献
17.
Takahashi M Saibara T Nemoto Y Ono M Akisawa N Iwasaki S Toda K Ogawa Y Wakatsuki A Inagaki S Onishi S 《Lipids》2003,38(7):687-692
The unique inborn hypertriglyceridemia seen in FLS (fatty liver Shionogi) mice was relieved by the administration of purified
apolipoprotein (apo) C-II. Lipoprotein lipase (LPL) and its cofactor, apoC-II, play a pivotal role in VLDL metabolism. Therefore,
we investigated the genetic background involved in this hypertriglyceridemia. Plasma levels of TG and total cholesterol as
well as LPL activity were measured in male FLS mice and C57/BL6J mice. Agarose gel electrophoresis and fast protein liquid
chromatography were used to analyze the lipoprotein profile. A cross experiment was done to determine the genetic background
of hypertriglyceridemia observed in FLS mice. cDNA sequences of apoC-II and apoC-III of FLS mice were determined. Preα-lipoprotein
was the predominant lipoprotein class in FLS mouse plasma. LPL activity remained in the range observed in C57/BL6J mice, and
purified apoC-II transiently relieved FLS mice from hypertriglyceridemia. Preα-lipoproteinemia was inherited in an autosomal
recessive manner. ApoC-III appeared to be a causal factor for this unique hypertriglyceridemia. Microsatellite analysis, however,
revealed that the responsible chromosome was not 7; rather, apoC-III mapped onto chromosome 9. Therefore, we suggest apoC-III
as a candidate causative factor for the hypertriglyceridemia observed in FLS mice because an excessive amount of apoC-III
attenuates LPL activity in vivo and in vitro. 相似文献
18.
Lipase (E.C. 3.1.1.3) from walnut seed was purified 28.6-fold with 31% yield using Sephadex G-100 gel chromatography. Olive
oil served as good substrate for the enzyme. The optimum pH and temperature were 9.0 and 70 °C, respectively. The lipase was
stable between 30 and 80 °C for 5 min. K
m and V
max values were determined as 48 mM and 23.06 × 10−3 U/min mg for triolein as substrate. Lipase activity was slightly reduced by Cu2+, Ca2+, Hg2+, Mn2+, and Ni2+ ions, while Mg2+ and Zn2+ had no effects. Anionic surfactant sodium dodecyl sulfate stimulated lipase activity while non-ionic surfactants Tween-80
and Triton X-100 had negligible effects on enzymatic activity. The enzyme activity was not affected by 50 mM urea and thioacetamide.
Potassium ferricyanide, n-bromosuccinamide and potassium cyanide reduced the enzyme activity. The enzyme showed a good stability in organic solvents,
the best result being in n-hexane (113% residual activity). The activity of dialysate was maintained approximately 80% for 1 year at −20 °C. 相似文献
19.
Phospholipase D (E.C. 3.1.4.4.) was detected in isolated bovine rod outer segments (ROS) and its properties determined. The
enzyme activity was assayed using either a sonicated microdispersion of 1,2-diacyl-sn-[23H]glycerol-3-phosphocholine (PC), or [14C]ethanol. Using [3H]PC and ethanol as a substrate, we were able to detect the hydrolytic properties as well as the transphosphatidylation reaction
catalyzed by phospholipase D (PLD): formation of [3H]phosphatidic acid and phosphatidylethanol [3H]PtdEt; whereas with [14C]ethanol or [3H]glycerol in the absence of exogenous PC, only transphosphatidylation reactions were detected (formation of [14C]PtdEt or [3H]phosphatidylglycerol, respectively). The use of varying concentrations of [3H]PC and 400 mM of ethanol gave an apparent K
m value for PC of 0.51 mM and a V
max value of 111 nmol × h−1 × (mg protein)−1. The activity was linear up to 60 min of incubation and up to 0.2 mg of protein. The optimal ethanol concentration was determined
to be 400 mM, with an apparent K
m of 202 mM and a V
max value for ethanol of 125 nmol × h−1 × (mg protein)−1. A clear pH optimum was observed around 7. PLD activity was increased in the presence of 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonate
or sodium deoxycholate and inhibited with Triton X-100. The enzyme activity was also activated in the presence of Ca2+ or Mg2+ (1 mM) although these ions were not required for measuring PLD activity. The high specific activity of PLD found in purified
ROS compared to the activity found in other subcellular fractions of the bovine retina suggests that this enzymatic activity
is native to ROS. The present report is the first evidence of PLD activity associated with photoreceptor ROS. 相似文献
20.
Haresh T. More Aniruddha B. Pandit 《European Journal of Lipid Science and Technology》2010,112(4):428-433
Ethanol‐soluble (ES) lecithin mainly contains phosphatidylcholine (PC). The incorporation of caprylic acid into PC using immobilized phospholipase A2 (PLA2) and lipase was investigated. The Rhizomucor meihei lipase and the porcine pancreatic PLA2 were immobilized on the hydrophobic resin Diaion HP‐20 and the modification was carried out in hexane as solvent. HPTLC with densitometer technique was successfully used for monitoring the production of structured phospholipids (PL) (ML‐type PC, MM‐type PC, and lysophosphatidylcholine; L: long‐chain fatty acid, M: medium‐chain fatty acid). The various parameters such as the effects of reaction temperature, enzyme loading, and the effect of molar proportion of substrate were studied in order to determine the optimum reaction conditions for the acidolysis reaction. The optimal operating conditions for the PLA2‐catalyzed reaction were obtained as 50°C temperature, 50% (wt/wt of substrate) enzyme loading, and a 1:12 molar proportion of PC/caprylic acid. For the lipase‐catalyzed reaction, the optimized temperature was the same as for PLA2, but the enzyme loading and molar proportion were slightly lower, i.e., 40 % w/w of substrate and 1:9 PC/caprylic acid, respectively. The effects of these parameters on the production of structured PL were compared. Under these optimal conditions, the ML‐type PC content was higher in the PLA2‐catalyzed reaction, i.e., 45.29 mol%, and in the lipase‐catalyzed reaction it was 38.74 mol%. 相似文献