Genetics of the kunitz trypsin inhibitor: An antinutritional factor in soybeans

The major trypsin inhibitor present in soybean seed [Glycine max (L.) Merrill] is the Kunitz trypsin inhibitor or soybean trypsin inhibitor A₂ (SBTI-A₂). Four types of SBTI-A₂9 have been identified in the U.S. soybean germplasm collection. Three of the types designated Ti^a, Ti^b, and Ti^c are electrophoretically distinguishable from one another by their different Rf values of 0.79, 0.75, and 0.83, respectively. The three types are inherited as codominant alleles in a multiple allelic system at a single locus. The fourth type which is the absence of SBTI-A₂ is found in P.I. 157440 and P.I. 196168. The gene for the lack of SBTI-A₂ is designated ti and is inherited as a recessive allele to the other three SBTI-A₂ 9 types. Ti^a is the most common SBTI-A₂ type in the germplasm collection. Linkage studies revealed that the SBTI-A₂ protein is inherited independently of certain morphological characters and chemical components of seed. Potential applications of the SBTI-A₂ types are discussed.     

Color,trypsin inhibitor and urease activity as it affects growth of broilers

In five experiments, the relationships among trypsin inhibitor contents, urease index and color in soybean meal (SBM), and the effects of those relationships on broiler chick performance were determined. Raw, solvent-extracted SBM was dehydrated to 2% moisture; then 0, 4, 8, 12, or 16% moisture was added and autoclaved at 120 C in sealed containers from 0 to 135 min with 15-min intervals. Urease and trypsin inhibitor contents decreased with either increasing moisture content or cooking time. With 16% added moisture, 30 min of cooking time was required to decrease urease index to an acceptable level, and 45 min was required to decrease trypsin inhibitor contents. Raw SBM autoclaved with less than 12% added moisture contained urease and trypsin-inhibitor contents that were not considered undesirable, regardless of cooking time used. Increased moisture and cooking time resulted in decreased trypsin inhibitor and urease contents, increased broiler growth, improved feed efficiency and decreased pancreas hypertrophy. Commercial SBM, containing 12 ug trypsin inhibited per mg of protein (μ/mg), a tristimulus+α (redness) color value of +3.21, and a urease index of 0.19 ΔpH, was autoclaved for 0–25 min with 5-min intervals to determine the effect of additional heat on broiler performance and SBM color. The commercial SBM, heated an additional 10 min, contained 1.77 μg trypgin inhibitor per mg of protein, a+a color value of +4.76, and urease index of 0.02 ΔpH. Broiler growth and feed efficiency were improved when the commercial SBM was heated an additional 10 min. Results of this study show that color is a good predictor of trypsin-inhibitor content and broiler chick performance. Color may be used to predict underprocessing, adequate, and overprocessing of SBM; however, trypsin inhibitor and urease index do not show the effect of overprocessing.     

Soybean trypsin inhibitor and urease activities and their correlations as affected by heating method,duration, sample matrix,and prior soaking

Urease activity (UA) in soybeans has historically been measured to indicate heating inadequacy. Yet, over the years, controversy has emerged regarding the reliability of UA as a heating index and surrogate for trypsin inhibitor activity (TIA). In Experiments 1–4, raw soybean materials with different matrices (whole beans, flakes, full-fat and defatted flours) were selectively subjected to steaming, boiling, or dry oven toasting for various durations. For steaming or boiling soybeans, with or without prior soaking was another factor. Reduction rates of TIA and UA with heating time were compared, their correlation coefficients were determined and statistically treated. Experiment 5 entailed collecting 30 commercial soybean meals and measuring TIA and UA without further treatments. By combining the five experiments into a single study, the most comprehensive spectra regarding relative decreasing rates of TIA and UA with heating time and their correlations were obtained. Results show that the reduction rate of UA could be slower than, close to, or faster than that of TIA, depending on combinations of four factors (sample matrix, with or without prior soaking, heating method and interval). UA reached zero within shorter heating durations, while TIA maintained residual values at the longest durations. Consequently, positive correlations between TIA and UA varied from insignificant to very strong. UA was a reliable index for heating inadequacy and surrogate for TIA in soybean products heated by several single combinations of the four factors, but for those heated by other single or mixed combinations, it was unreliable, and TIA should be measured directly.     

土壤脲酶及脲酶抑制剂

本文介绍了影响尿素利用率的主要因素和一种新型脲酶抑制剂的研究方法。     

Chemical composition and lipoxygenase activity in soybeans as affected by genotype and environment

Environmental and genetic influences on the chemical composition and lipoxygenase activity of 24 soybean genotypes (groups IV-S and V) were determined. The soybeans were grown at two climatically different locations within the state of Georgia. Oil and protein contents and fatty acid composition of the oil in soybeans were affected by the environment. Five genotypes from group IV-S has a fatty acid composition of the oil different from the other genotypes in the group. These differences appeared to be genetically controlled. The level of lipoxygenase activity in soybeans also appeared to be genetically controlled and not influenced by the environment. The study indicated that soybean genotypes could be selected for a specific climatic region based on oil fatty acid composition and lipoxygenase activity.     

Effect of heat inactivation of lipoxygenase on lipid oxidation in lake herring (coregonus artedii)

The role of lipoxygenase in causing lipid oxidation in lake herring was studied. Lipid oxidation was measured by assaying for 2-thiobarbituric acid-reactive substances (TBARS), and lipoxygenase activity was measured by a spectrophotometric (470 nm) method. Lipoxygenase activity was highest in light muscle, lowest in skin and intermediate in dark muscle. Light muscle contained the highest percentage of phospholipids (PL) and the least total lipid. The percentage of PL was lowest and total lipids were highest in the skin. Eicosapentaenoic acid and docosahexaenoic acid were found in larger amounts in PL than in triglycerides. Heat treatment rapidly inactivated lipoxygenase. After a 5-min heating period, lipoxygenase was totally inactivated in most cases. TBARS data indicated that samples heated at 80°C for 1.5–2.0 min were more stable than samples heated at 80°C for 2.5–5.0 min, suggesting that heat accelerated nonenzymatic oxidation.     

Nitric oxide,an inhibitor of lipid oxidation by lipoxygenase,cyclooxygenase and hemoglobin

The present study demonstrated that nitric oxide, which is an important mammalian metabolite, can inhibit oxidation by lipoxygenase, cyclooxygenase and hemoglobin. The inhibition is manifested as a lag-phase that is reversible. The inhibitory effect of nitric oxide on lipoxygenase and cyclooxygenase seems to derive from i) the capability of ·NO to reduce the ferric enzyme to the ferrous form, which is inactive; ii) competition for the iron site available for exogenous ligands; and iii) the radical scavenging ability of the nitroxide radical. Nitric oxide may act as a modulator of the arachidonic acid cascade and in the generation of oxygen-active species.     

Synthesis,crystal structure and urease inhibitory activities of Schiff base metal complexes

Six new transition metal complexes (1–6) with Schiff base were synthesized and crystallographically characterized. Their urease inhibitory activities were evaluated. Three of them showed potent inhibitions against jack bean urease. Mn(II) complex (2) possessed the best jbU inhibitory activity with IC₅₀ of 8.30 ± 0.93 μM, which was much better than those of the corresponding ligand and control ion. The investigation on the stability constants and the structure-activity relationships of the complexes indicated that the complexes interacted with the enzyme in the whole complex forms rather than the free ions.     

Minimizing protein insolubilization during thermal inactivation of lipoxygenase in soybean cotyledons

The objective was to develop a procedure for inactivating lipoxy-genase in soybean cotyledons without losing protein solubility. The approach was to moisten cotyledons to one of 2 levels in soft water or carbonate buffers, steam for a short time, hold for a definite period at a known temperature, cool and analyze for enzyme activity and protein solubility. Temperature dependence of both inactivation and insolubilization kinetics was determined. Increasing temperature of steaming and holding favored our objective. At 16.3% moisture, the pH 9.8 buffer was beneficial but the pH 10.8 buffer was not. The holding period was not beneficial compared to steaming alone. Recommended conditions were adjustment of cotyledon moisture to 16.3% with pH 9.8 buffer and then heating in steam for about 10 sec; at temperatures of 91 C and above, 99% of the lipoxygenase could be inactivated with retention of over 70% protein solubility. The effect of buffers on kinetics of heat inactivation and insolubilization appeared to be related to the states of hydration water, i.e., the presence of solute water at the higher moisture content.     

Further compositional analyses of flax: Mucilage,trypsin inhibitors and hydrocyanic acid

Registered Canadian cultivars of flax, and laboratory-prepared and commercially obtained samples of linseed meal (LM), were used to determine extract viscosity and mucilage, trypsin inhibitors and hydrocyanic acid (HCN) concentrations. The mucilage readily leached out from the seed coat (hull) fragments soaked in water, leaving behind pentagon-shaped cells that could be seen clearly in scanning electron micrographs. Extract viscosity significantly varied in the laboratory-prepared (23–48 cS) and commercially obtained (30–68 cS) samples of LM and may be used to obtain an indirect, qualitative estimate of flax mucilage. Mucilage was extracted from whole seed in 5.0–5.3% yields and contained 20–24% protein (about 10% ash and 30% total carbohydrates). Laboratory-prepared LM (raw) contained 42–51 units of trypsin inhibitor activity, commercially obtained samples, 14–37 units, and raw rapeseed and soybean meals, 99 and 1650 units, respectively. Picric acid tests (qualitative) showed only traces of HCN in ten cultivars of freshly ground flax. The acid silver nitrate titration procedure measured HCN quantitatively, but showed its presence only in three of the five cultivars investigated. HCN was conveniently measured by a colorimetric procedure (barbituric acidpyridine reaction), which may be used to screen flax cultivars. HCN content of flax was significantly influenced by environments (growth location and season) and, to a less extent, by cultivar.     

Bis-phosphatidic acid in developing soybeans and soybean suspension cultures

A phospholipid which rapidly accumulates radioactivity from [1-¹⁴C] acetate administered to slices of developing soybeans or to suspension cultures of soybean cells was isolated. Its structure was identified by comparison of its properties and degradation products with those of authentic lipid standards using infrared absorption spectrometry, thin layer chromatography, acetolysis, mild alkaline hydrolysis, and determination of molar ratios of phosphorus, glycerol, and acyl moieties. The structure of the phospholipid was found to bebis-phosphatidic acid, a phospholipid previously unreported in higher plants.     

Dimorphotheca sinuata lipoxygenase: Formation of 13-L-hydroperoxy-cis-9,trans-11-octadecadienoic acid from linoleic acid

Lipoxygenase (EC 1.13.1.13) from the seed ofDimorphotheca sinuata oxidized linoleic acid to predominantly 13-L-hydroperoxy-cis-9,trans-11-octadecadienoic acid. When the reaction proceeded at pH 6.9, the 13-hydroperoxide was the only isomer detected; but at pH 5.1, the 13-isomer was 92% of the total, the remaining 8% being the 9-hydroperoxide. At both pH's small amounts of hydroxyoctadecadienoic acid accumulated during the reaction. This acid from the pH 6.9 reaction was analyzed as 13-hydroxy-cis,trans-octadecadienoic. The postulate advanced by many workers that dimorphecolic acid, 9-D-hydroxy-trans-10,trans-12-octadecadienoic acid, is biosynthesized via a lipoxygenase product was not proved. Although the product specificity ofD. sinuata lipoxygenase is like that of lipoxygenase type 1 from soybeans, its inactivity at pH 9 demonstrated that it is a novel enzyme. ARS, USDA.     

Chitosan Schiff base as effective corrosion inhibitor for mild steel in acid medium

An environment friendly inhibitor, chitosan thiophene carboxaldehyde Schiff base, was synthesized by a condensation reaction of the carbonyl group of thiophene 2‐carboxaldehyde and free amino groups of chitosan. The chitosan Schiff base was characterized by UV spectroscopy, Fourier transform IR spectroscopy, elemental analysis and thermal analysis. The surface morphology of the Schiff base derivative was examined by SEM. Gravimetric and electrochemical techniques were used to explore the behaviour of the chitosan thiophene derivative as a corrosion inhibitor for mild steel in an acidic environment. The effects of inhibitor concentration, exposure time and temperature were investigated. The chitosan Schiff base showed a good inhibition performance of 92% inhibition efficiency at room temperature for 12 h of immersion in a weight loss experiment. The electrochemical results showed that the chitosan derivative acts as an effective mixed type inhibitor. The adsorption of the inhibitor followed the Temkin isotherm model. SEM and AFM techniques were used to characterize the protective layer formed on the mild steel substrate. © 2016 Society of Chemical Industry     

润滑油基础油技术及添加剂发展现状

随着高精密机械、汽车的发展,社会对润滑油的需求更加紧密。润滑油主要由基础油和添加剂组成,基础油成分占70%～99%。基础油的质量决定了油品的品质。主要介绍基础油的生产方法、润滑油的分类标准和添加剂的发展状况。     

Effect of feeding soy products with varying trypsin inhibitor activities on growth of shrimp

Six isonitrogenous, isocaloric diets containing commercially defatted, toasted and lightly toasted soy flours (SF) (diets 1 and 2) and four soy protein concentrates (SPC) (diets 3–6) as replacements for 40% of animal protein were fed to satiation to juvenile shrimp (Penaeus vannamei) for 10 weeks. The SPCs used in diets 3 and 5 were chemically modified products with reduced trypsin inhibitor (TI) content. The chemical modification of SF in diet 2, which resulted in an SPC for diet 3, and of SPC in diet 4 consisted of heating at 70°C for 1 hr with 50 mM Na₂S₂O₅, followed by dialysis to remove salt residues. To keep all diets isocaloric, cornstarch was added to replace the oli-gosaccharides lost during processing to an SPC. The TI contents, in mg TI/g diet, were 0.77, 6.14, 0.64, 1.40, 0.92 and 1.72 for diets 1–6, respectively. Shrimp fed lightly toasted SF had the highest weight gain, which was significantly higher than shrimp fed SPC diets 4, 5 and 6, but not significantly higher than shrimp fed diets 1 and 3. No significant difference was observed in survival rates. Shrimp fed diet 3 (with lowest TI) had the highest body percentages of crude protein, while toasted soy flour diet 1, also with low TI, had the lowest content of this constituent. In general, a high body protein reflects good health of the animal and excellent utilization of the feed. At the replacement levels of soy evaluated, TI content did not affect overall weight gain. Presented at the 1991 AOCS Meeting, May 12–15, 1991, Chicago, IL.     

Influence of urea fertiliser formulation, urease inhibitor and season on ammonia loss from ryegrass

This paper reports the results of experiments to determine whether ammonia (NH₃) loss can be reduced and nitrogen (N) use efficiency improved by using two relatively new commercial urea formulations rather than granular urea and urea ammonium nitrate. Four nitrogen treatments were applied at a rate of 40 kg N ha^?1: granular urea, ‘Green Urea? 14’ [containing 45.8 % N as urea and ‘Agrotain^®’ (N-(n-butyl) thiophosphoric triamide) @ 5 L t^?1 of urea as a urease inhibitor], ‘Nhance’, a fine particle spray [containing 46 % N as urea, ‘Agrotain’ @ 1 L t^?1 of urea and gibberellic acid (applied at a rate of 10 g ha^?1)] and urea ammonium nitrate in solution (UAN) surface applied. Ammonia loss was determined in autumn and spring using a micrometeorological method. In autumn, use of the Green Urea and Nhance reduced NH₃ loss from the 30 % of applied N lost from the granular urea to 9 and 23 % respectively. Loss from all treatments in spring was very small (<2 % of applied N), because 4 mm of rain fell within 24 h of application onto an already wet site. The use of the Nhance and Green Urea instead of granular urea did not result in increased agronomic efficiency or recovery efficiency of the applied N, and this is most likely due to the presence of sufficient available N from both fertiliser application and the soil. A ¹⁵N study recovered 72.8 % of the applied N in the plants and soil, and showed that 30 % of the total N taken up by the plant was derived from the fertiliser, and 70 % from the soil.     

Immobilized lipoxygenase in continuous production of fatty acid hydroperoxides

Soybean lipoxygenase-1 was covalently coupled to agarose with 75% recovery of catalytic activity. Because evidence was obtained that the immobilization resulted in improved operational stability of the enzyme, a lipoxygenase-reactor and a continuous process for the synthesis of 13-hydroperoxy-linoleic acid and 15-hydroperoxyarachidonic acid were developed. A procedure based on spectrophotometric hydroperoxide assay and constant oxygraphic monitoring of the effluent is presented for the calibration of the reactor to operate at the highest conversion efficiency when oxygenating quantitatively the substrate. Under these conditions, the reactor was capable of producing about 0.6 mg of hydroperoxy fatty acid/1.0 ml of wet gel/hr. The covalently coupled enzyme has been stable during six months of storage at 3 C in 0.2 M Na-borate buffer, pH 9.0, and during the same period, its operational stability in the column has been unaltered under the conditions used.     

添加剂在盐酸电解中的应用

介绍盐酸电解的反应机理，分析槽电压的影响因素，指出盐酸电解时，向其中添加PtCl4和PtCl2，可以达到节约电能、增加经济效益的目的。     

Physical state of inhibitor fatty acids and linoleate solutions under lipoxygenase assay conditions

A variety of fatty acids, which are potential competitive inhibitors of soybean lipoxygenase (EC 1.13.11.12), give kinetically unstable mixtures in standard assay solutions containing linoleate (substrate). In the assay solution (pH 10, 0.1 M borate, 1.63% ethanol), each fatty acid by itself shows normal surface tension vs concentration behavior; but, despite a range of solubilization techniques in the presence of 10 μM or higher linoleate and low concentrations of these materials, irreproducible surface-tension readings and inhibition kinetics results. This inhomogeneity (or kinetic instability) disappears as the concentration increases. Critical micelle concentration (CMC) values of mixtures are not additive, and binary mixture behavior depends on fatty acid structure. Several lines of observation, including CMC values and actual surface tension (γ) values for several systems, suggest premicellar heterodimer or higher mixed aggregate formation. Lipids with K_i significantly above the irreproducible surface-tension range give good kinetic behavior, and K_i is reported. The results are in accord with earlier work on aspects of these systems. Complementary solution physical studies must be done for any kinetic (or specificity) determinations of enzymes using lipids. The notation for fatty acids follows the system in which a,b-x:y indicates a fatty acid of x carbons with ycis double bonds at positions a and b from the CO₂H;trans olefin is designated by (t) following the position number; SC₁₀S and SC₁₂S are sodium decyl and sodium dodecyl sulfates; 9,12(OH)-18∶1 is ricinoleic acid; CMC is critical micelle concentration. Surface tension is γ.