Molecular Weights,Lengths, and Distribution of Side-chains in α-D-Polyglucanes

Freshly prepared starch (from potatoes P, from maize M) was separated quantitavely into amyloses and amylopectins under mild conditions. Furthermore, glycogen (G) was extracted from livers of rabbits under observation of physiological provisoes (feeding, rapid removal of the organ under anaesthetic and freezing-stop). The molecular weights, determined by analytical ultracentrifuge . The side-chain parts of the amylopectins and of the liver glycogen which were checked by partial enzymatic break-down into β-dextrin by β-amylase (EC 3.2.1.2) and into the basic structure by pullulanase (EC 3.2.1.41) is 64% for P, 62.7% for M, and 65.4% for G. The lengths of the side-chains, expressed in glucoside residues, are calculated at 12.0 for P and M, and 8.0 for G; the intervals between the side-chains are 7.0 for P and M, and 4.0 for G. Sources of error with respect to the lengths of and to the intervals between the side-chains are, firstly, free-ending, undecomposed side-chains inside the big molecules which cannot be reached by the two enzymes because fo steric obstruction, and, secondly, the degree of ramification of the basic structures and, consequently, the number of α-1,4 and α-1,6-bound glucoside residues which cannot be split off by pullulanase.     

银杏支链淀粉分子结构的研究

应用酶法研究了银杏支链淀粉的精细分子结构。结果显示银杏支链淀粉的平均链长、外链和内链长分别为２５、１７和７：用异淀粉酶和普鲁兰酶作用于银杏支链淀粉β－极限糊精,得到银杏支链淀粉的Ａ、Ｂ链比值为１．６８：１,分支化度为２．６８。此结果也证实支链淀粉在生物体内的形成并非来源于糖原的前体物质。     

Molecular Structure of Banana Starch

Starch isolated from green banana fruit was hydrolyzed with pullulanase and β-amylase and the hydrolyzates fractionated on Sephadex G-50 and G-100. Debranching of the starch and it β-limit dextrin with pullulanase revealed that banana amylopectin had populations of d?.p?. 45 and d?.p? 15 chains in a molar ratio of 1:6. The average chain length of the debranched starch and the debranched β-limit dextrin was 26 and 10, respectively. The amylose content was 16%. Amylose prepared by selective leaching and by thymol complexation had β-amylolysis limits ≥ 92%.     

Inhibition of digestive enzymes by condensed tannins from green and ripe carobs

The degree of inhibition of trypsin, β-amylase and lipase by condensed carob tannins was determined, and compared with that caused by a glucoside of m-digallic acid. the carob tannins were strongly inhibitory to all the enzymes assayed; β-amylase was the most sensitive and lipase the least sensitive. Only in the case of lipase was the hydrolysable tannin a more active inhibitor than the condensed carob tannins. Polyvinyl pyrrolidone reactivated trypsin and lipsse, but not β-amylase. The inhibitors were found to change the maximum reaction velocities of crystalline trypsin and β-amylase, indicating non-competitive reaction kinetics.     

Physicochemical Properties of Sweet Potato Starches

The physicochemical properties of the starches from three varieties of sweet potatoes were investigated. The crystalline structures of Koganesengan and Minamiyutaka starches were of the A type and that of Norin-2 starch was of the Ca type. Their amylograms showed pasting temperatures of 73–75°C and maximum viscosities of 500–580 BU. 3-Methyl-1-butanol lowered their pasting temperatures without altering their maximum viscosities. The amylose and organic phosphorus contents of the starches were 17.2–19.0% and 117–139 ppm, respectively. The amyloses comprised branched molecules of average degree of polymerization 3400–4400 with 10–13 chains on average and were hydrolyzed 72–73% by β-amylase. The main amylopectins had average chain lengths of 21–22, β-amylolysis limits of 55–56% and organic phosphorus contents of 117–144 ppm, of which 75–81% was attached to C–6 of the glucose residue and the remainder to C–3. Another type of amylopectin (10–15% of the starch), which had higher iodine affinity, was isolated.     

Glykogene,Glykogen-Iodkomplexe, β-Dextrine, β-Dextrin-Iodkomplexe aus Geweben des Rindes und des Kaninchens

Glycogens, Glycogen-Iodinecomplexes, β-Dextrins, β-Dextrin-Iodinecomplexes in Bovine Tissues and Tissues of Rabbit Glycogen fractions were prepared from bovine and rabbit tissues and the molecular weights were determined by analytical ultracentrifugation. With these glycogens the generation of iodine complexes was studied and the beginning of the colour reaction and the saturation point was determined. From the minimal and maximal iodine accumulation the number of glucoside residues/iodine molecule was calculated and the results were used for the estimation of the distance between two side chains and the length of the side chains. Further glycogen preparations were treated with β-amylase and degradation rates of 40–47% of the sample were gained by maltose separation. The generated β-dextrine were also used for the determination of β-dextrine/iodine complexes. The distance between two side chains in the animal glycogen amounts from 4 to maximally 6 glucose residues, the side chains consist of an average of 8 units. The animal glycogens were found to be different in molecular weight and in the structure which are related to the function of the tissues.     

The Fine Structure of Corn Starches of Various Amylose-Percentage: Waxy,Normal and Amylomaize

The fine structure of high-amylose corn starches has been studied after dispersion of the starch and fractionation into their components amylose and amylopectin. The resulting amylopectin fraction reported in the literature possesses anomalous properties with regard to the waxy and normal amylopectin. However, the experimental results obtained by different authors for determining the structure lead to controversal explanations. Therefore, using an enzymic method, which permits the direct examination of the constitutive chains of the starch, the fine structure of the amylopectin of an amylomaize starch (64% amylose) has been investigated and compared with those of waxy and normal starches. The pullulanase – debranched chains are fractionated by gel permeation and their linearity are checked under the action of β-amylase. The inner chains of the amylopectin fraction are studied after debranching of the β-limit dextrins. The results show the identity between amylopectins from waxy and normal starches. The amylopectin fraction of amylomaize has its own structure with longer inner chains than those of waxy-maize amylopectin.     

Studies on the Non-cyclic Products of the Cyclodextrin Glycosyltransferase from Klebsiella pneumoniae M 5 al. Isolation and Characterization of Highly Branched Clusters from Digests with Manioc Starch

49.4% of manioc amylopectin was recovered as non-cyclic products from 48 h digests of the starch with cyclodextrin glycosyltransferase [1, 4-α-D-glucan: 1, 4-α-D-glucopyranosyltransferase (cyclizing) EC 2.4.1.19] from Klebsiella pneumoniae M 5 al. Highly branched clusters of different sizes (average degree of polymerisation 26.9 - 173) were obtained by fractionation. The extents of β-amylolysis varied between 16.6 - 23%, indicating that the cyclodextrin glycosyltransferase has left larger parts of unsubstituted (mainly A-), and the exterior B-chains. By debranching with pullulanase, and analysis of the linear chains, it was evident that the β-limit dextrins of the fragments contained populations of longer chains, carrying branching points near the non-reducing chain ends. From the molar distribution of the chains, calculated from the data obtained by quantitative h.p.l.c., indications of the structure of the branched fragments were obtained 3.5% of the amylopectin was found to be glucose to maltotetraose, indicating that coupling and disproportionation reactions were negligible even in the course of long-term incubation. The smallest branched saccharides were found to be fragments with 6 D-glucose residues.     

The Interaction of the Amylose-Extender and Waxy Mutants of Maize (Zea Mays L.) Fine Structure of Amylose-Extender Waxy Starch

Investigations into the nature of the effect of the amylose-extender (ae) mutant of maize (Zea mays L.) on amylopectin structure were conducted by studying the fine structure of amylose-extender waxy (ae wx) starch. Approximately 59.6% of the starch from ae wx endosperms was converted to maltose by β-amylase. This starch contained 21% apparent amylose and had a λmax of 580 for the iodine-starch complex. Fractionation of ae wx starch on Sepharose 4B-200 gave an elution profile with a single peak characteristic of amylopectin. From these observations we concluded that ae wx starch consisted of an altered amylopectin, with iodine binding properties such that an apparent amylose content of 21% was measured. The fine structures of ae wx and waxy (wx) starches were determined. Pullulanase-debranched chains of whole starches and β-limit dextrins were fractionated by gel permeation. The amylopectin of ae wx was shown to be a loosely branched amylopectin with an average internal chain length of 52 glucose units compared with a length of 30 glucose units for wx. The ae wx outer chains were longer than those of wx and fewer in number per mg of starch. These characterizations demonstrate that ae wx starch has a unique structure which is similar to the anomalous amylopectin reported in ae starch.     

超高麦芽糖浆的生产

本文研究了超高麦芽糖浆的生产，结果发现，普通β－淀粉酶和脱支酶共同作用适于制造普通非结晶性麦芽糖浆，组成大致为８０％左右的麦芽糖和１０％左右的麦芽三糖，而外切型α－麦芽糖－α－小淀粉酶（Ｍａｌｔｏ－ｇｅｎａｓｅ）由于价格及水解方式两方面的原因，不适合用于此类麦芽糖浆的生产。但生产用于制造结晶麦芽糖的超高麦芽糖浆时，则宜用β－淀粉酶、Ｍａｌｔｏｇｅｎａｓｅ和脱支酶共同作用，通常的组成为８０％以上的麦芽糖，４％以下的麦芽三糖。     

Synthesis of Heptakis (2-O-methyl)-β-cyclodextrin

The title compound was prepared by a reaction sequence comprising methylation of heptakis (6-bromo-6-deoxy)-β-cyclodextrin by the Kuhn procedure, regeneration of the primary hydroxyl groups from the resulting heptakis(2-O-methyl-6-bromo-6-deoxy)-β-dextrin via the 6-O-benzoate ester by benzoate exchange and subsequent deesterification. It was proved that the methyl groups in the tetradeca-O-methyl ether of β-dextrin are located 0–2 and 0–6 of the D-glucose residues.     

PHYSICOCHEMICAL CHARACTERISTICS OF YAM STARCHES

Starch from tubers of Dioscorea alata, Dioscorea cayenensis, Dioscorea dumetorum, and Dioscorea rotundata was isolated and some of the important characteristics determined. Amylose and amylopectin fractions were obtained by aqueous leaching technique. All the starches appeared to have definite but minor differences in iodine binding capacity, swelling power, solubility, intrinsic viscosity, and amylose/amylopectin ratio. Brabender amylogram of each starch showed no distinct peak viscosity, and the general amylograph pattern was distinctly different from typical amylographs of cereal starches. Amylose fractions from each starch variety exhibited variable degree of β-amylolysis limits ranging from 92–97.5%, and an average molecular weight for amylose triacetate of 210,000 to 265,000. Amylopectin fractions subjected to debranching by pullulanase gave essentially two chain populations of polysaccharides with degree of polymerization of approximately 13–27 and 47–65, respectively. Average unit chain length of the amylopectins ranged from 19 in Dioscorea rotundata to 24 in Dioscorea dumetorum.     

Purification and Characterization of β-amylase from Bacillus polymyxa No. 26-1

An extracellular β-amylase, which was easily adsorbable onto raw corn starch, was purified 22.5-fold from a new isolate of Bacillus polymyxa No 26–1 with a M_r of 53 kDa and pI of 9.1. The optimum temperature was 45°C and pH 5.5 for raw corn starch. Thermal stability at 40°C and pH stability at 5.0–8.5 were shown. The degradation ofraw starch by β-amylase was greatly stimulated by pullulanase addition. Scanning electron micrographs revealed that starch granule degradation by the enzyme alone occured at the equatorial grooves of lecticular granules. Corn starch granules hydrolyzed by β-amylase had large holes on granule surfaces.     

Purification and Characterization of a Maltotriogenic α-Amylase I and a Maltogenic α-Amylase II Capable of Cleaving α-1,6-Bonds in Amylopectin

Extracellular α-amylases I and II, produced by a facultative thermophile Bacillus thermoamyloliquefaciens KP 1071 capable of growing at 30–66°C, were purified to homogeneity. α-Amylase I consisted of a single polypeptide with methionine residue at the NH₂-terminus. α-Amylase II consisted of two equivalent polypeptides each comprising a methionine at the NH₂-terminus. α-Amylase I hydrolyzed endotypically α-1,4-bonds in glycogen, amylopectin and β-limit dextrin, but not their α-1,6-bonds. α-Amylase II degraded amylopectin and β-limit dextrin in exo-fashion by cleaving preferentially α-maltose units from the non-reducing ends and hydrolyzing their α-1,6-branch points. α-Amylase II hydrolyzed maltotriose, phenyl-α-maltoside, α- and β-cyclodextrins and pullulan, whereas α-amylase I had no activity for all these sugars. α-Amylases I and II hydrolyzed maltotetraose, maltopentaose, α-limit dextrin and amylose, but they were inactive for maltose, isomaltose and panose. It was suggested that α-amylase I is the most thermostable type of hitherto known maltotriogenic endo-acting α-amylases, and α-amylase II is the first maltogenic exo-acting α-amylase able to split α-1,6-bonds in amylopectin.     

Amidons Lintnérisés Etudes chromatographique et enzymatique des résidus insolubles provenant de l'hydrolyse chlorhydrique d'amidons de céréales,en particulier de maïs cireux

Lintnerized Starches. Chromatographic and Enzymatic Studies of Insoluble Residues from Acid Hydrolysis of Various Cereal Starches, Particularly Waxy Maize Starch . Native cereal starches, particularly waxy maize starch, have been carefully hydrolyzed at 35°C with hydrochloric acid (2,2-N) in heterogeneous phase. Observation of the course of hydrolysis as a function of time makes it possible to classify the starches according to their acid lability. The kinetic values distinctly reveal two phases, i.e. a fast hydrolysis of the amorphous fraction and a slower degradation of the crystalline starch grain fraction. This observation was confirmed by X-ray diffractometric patterns. The hydrolysis speed of acid resistant fractions seems to become slower as the apparent amylose ratio increases. The change in the macromolecular structure of the obtained granular residues or “lintnerized” starches as a function of time was examined after aqueous solubilization by means of gel chromatography using a calibrated Sephadex G-50 column. Lintnerization causes a decrease in the apparent DP of the chains of the starch residues and two subgroups with apparent DP 13 and 25 appear rapidly. These DP are unchanging with time of acid treatment. The chromatographic and enzymatic studies of lintnerized starches were performed directly and after successive enzymatic digests with pullulanase and ß-amylase. After debranching of solubilized residues with pullulanase and gel chromatography a linear chain subgroup of DP 15–20 appears. This one is in fact composed of two subgroups: one more important with a DP 13, the other broad distribution with a DP 15–25. The comparison with the subgroups observed before debranching shows that a main part of the initial subgroup of DP 25 could be considered as formed with singly branched chains. Furthermore a small proportion of pullulanase resistant ß-limit dextrins was obtained. The obtained results permits one to suggest a new model for the structure of waxy maize amylopectin. On the basis of this model the differences in structure existing between the various starches are discussed and the results are compared with those reported elsewhere for potato starch. A parallelism between crystalline patterns of native starches and the amylopectin structure, particularly its branching degree, is observed.     

Die Wirkung von α-Amylasen auf β-Cyclodextrin und der Nachweis von α-Amylasefremdaktivitäten in ausgewählten Enzympräparaten

The action of α-amylases on β-cyclodextrin and the evidence of foreign activity of α-amylase in selected preparations of enzymes The interaction between cyclodextrins and α-amylases taken from different sources is discribed contradictious in the literature. Some α-amylases e.g. isolated from Aspergillus oryzae, porcine pancreas and saliva hydrolized cyclodextrins to glucose. The hydrolysis of cyclodextrins catalysed by α-amylase from Bacillus species have been described conflicting. In this paper the action of hydrolysis of different preparations of α-amylases on β-cyclodextrin have been investigated. It has been shown that Rohalase M3 (α-amylase from Aspergillus niger) cleaves the ring of β-cyclodextrin. 2 α-amylases from Bacillus subtilis are not able to hydrolyse β-cyclodextrin. The reasons for the different actions of hydrolysis have been discussed with size and structure of the active centre of the enzymes. Moreover, different preparation of hydrolysis have been tested on secondary activity of α-amylase. 2 glucoamylases from Aspergillus oryzae have been shown secondary activity of α-amylase. With the hydrolases α-glucosidase from fungies, β-amylase from malt, saccharase from yeast, invertase from S. cerevisiae and pullulanase from Aerobacter aerogenes no cleavage of the ring of β-cyclodextrin could be detected.     

Comparative Study on the Starch Noodle Structure of Sweet Potato and Mung Bean

ABSTRACT:  Fine structure of sweet potato starch (SPS) and mung bean starch (MBS) by gel-permeation chromatography (GPC) showed that the amylose in SPS and MBS had 9.0 and 1.8 chains, respectively. The long chains of amylopectin in MBS (A_p-MB) were longer than those of amylopectin in SPS (A_p-SP), but the short chains of A_p-SP were shorter than those of A_p-MB. The structures of starch noodles of sweet potato (SPSN) and mung bean (MBSN) were analyzed by GPC, scanning electron micrograph (SEM), differential scanning calorimetry (DSC), and X-ray diffraction after hydrolysis by acid and enzymes. The results showed that the residues obtained with acid and enzymes in MBSN contained large amounts of high molecular weight fractions, and a relatively small amount of low molecular weight fractions, whereas those in SPSN contained some high molecular weight fractions and large amounts of low molecular weight fractions. SPSN exhibited higher digestibility by HCl, α-amylase, β-amylase, and pullulanase than MBSN. The surface of MBSN was more smooth than that of SPSN and the inside of MBSN contained long, thick, and orderly filaments, while there were many pore spaces inside SPSN from SEM. The DSC thermogram of the resistant residues from both starch noodles after acid/enzyme hydrolysis showed a broad endotherm peak near 100 °C (96 to 115 °C) due to the presence of the complexes of amylose-lipid and lipid-(long chains in amylopectin). Because of a lower content of branched amylose and a higher content of amylopectin in SPS, the structure of SPSN had a less distinct crystalline pattern and higher adhesiveness, whereas there was a higher content of amylose with a little branch and moderate amylopectin in MBS. Thus, the structure of MBSN had a stronger distinct crystalline pattern and good cohesiveness.     

α-Amylolysis of native potato and corn starches - SEM, AFM, nitrogen and iodine sorption investigations

Scanning electron microscopy (SEM), atomic force microscopy (AFM), as well as iodine and nitrogen sorption measurements were applied to investigate potato and corn starch granules surface after an action of Bacillus subtilis α-amylase. The SEM images revealed holes and pits (corn starch) or scratches (potato starch) on the surface of modified granules. These results were confirmed by AFM investigation which showed the presence of depressions of approximately 121 nm in diameter. Structure of the surface was not uniform. It consisted of small particles, amylopectin blocklets, of approximately 20 nm in diameter. They became more distinctive after α-amylolysis. Values of iodine binding capacity (IBC) obtained for hydrolyzed granules were lower than for native ones which indicated that the amylose and amylopectin chains building their surface were shortened. Specific surface area, volume and average diameter of mesopores increased for both starches after α-amylolysis.     

Photometrische Titration der Särkepolysaccharide mit Jod. II. Mitt. Hydrolyse mechano-chemisch abgebauter Amylose durch β-Amylase

Photometric Titration of Starch Polysaccharides by Iodine. Part 2: Hydrolysis of Mechano Chemically Degraded Amylose by β-Amylase. With photometric titration of amylose by means of iodine, the course of the graph depends on molecular weight distribution, average molecular size and concentration of polysaccharides. Respective data are: size of the linear part of the titration graph, total iodine concentration at half saturation of amylose by iodine, and maximum value of extinction. This new method is applied to examine β-amylolysis of natural amylose of various molecular size. High-molecular substrates are degraded according to a single-chain mechanism and amyloses having been swing-milled for more than 48 h are degraded by a multichain mechanism. The change in the effect of β-amylase occurs in the range between P_n 130 and 200, This change is to be contributed to differences in the molecular configuration of the substrate.     

Oat Starch: Some Recent Developments

Starches from Canadian oat varieties have been examined. Iodine affinity, solubility and λ_mzx of the iodine complex are lower than those found for other cereal starches. Swelling power, limiting viscosity number and hot paste cooling curves are all higher than for other cereal starches. Gel chromatography reveals a fraction of molecular weight between amylose and amylopectin and which is present in greater amount than that found in wheat starch. The β-amylase digestion limit is lower than that found for wheat and corn and may suggest a more branched structure for oat starches.