Mixture Of Maltose Research Articles

Physiological role of beta-phosphoglucomutase in Lactococcus lactis.

A beta-phosphoglucomutase (beta-PGM) mutant of Lactococcus lactis subsp. lactis ATCC 19435 was constructed using a minimal integration vector and double-crossover recombination. The mutant and the wild-type strain were grown under controlled conditions with different sugars to elucidate the role of beta-PGM in carbohydrate catabolism and anabolism. The mutation did not significantly affect growth, product formation, or cell composition when glucose or lactose was used as the carbon source. With maltose or trehalose as the carbon source the wild-type strain had a maximum specific growth rate of 0.5 h(-1), while the deletion of beta-PGM resulted in a maximum specific growth rate of 0.05 h(-1) on maltose and no growth at all on trehalose. Growth of the mutant strain on maltose resulted in smaller amounts of lactate but more formate, acetate, and ethanol, and approximately 1/10 of the maltose was found as beta-glucose 1-phosphate in the medium. Furthermore, the beta-PGM mutant cells grown on maltose were considerably larger and accumulated polysaccharides which consisted of alpha-1,4-bound glucose units. When the cells were grown at a low dilution rate in a glucose and maltose mixture, the wild-type strain exhibited a higher carbohydrate content than when grown at higher growth rates, but still this content was lower than that in the beta-PGM mutant. In addition, significant differences in the initial metabolism of maltose and trehalose were found, and cell extracts did not digest free trehalose but only trehalose 6-phosphate, which yielded beta-glucose 1-phosphate and glucose 6-phosphate. This demonstrates the presence of a novel enzymatic pathway for trehalose different from that of maltose metabolism in L. lactis.

Synthesis of alpha-D-glucosylglycerol by alpha-glucosidase and some of its characteristics.

It has been found that alpha-D-glucosylglycerol (GG) is contained in such traditional Japanese foods brewed by using koji as sake, miso and mirin, and that GG is formed by transglucosylation to glycerol that is produced by yeast with alpha-glucosidase (EC 3.2.1.20) from koji in the sake mash. GG has also been found to consist of three components, 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG was synthesized from a mixture of maltose and glycerol by the batch method, using alpha-glucosidase (transglucosidase L-AMANO). alpha-Glucosidase seemed to be so stable that the amount of GG increased about 5-fold compared with that in the first reaction by the daily addition of maltose for 10 d. Syrupy GG obtained was found to have the following characteristics: about 0.55-fold sweetness compared with sucrose, high thermo-stability, low heat-colorability, low Maillard reactivity, low hygroscopicity, high water-holding capacity, non-cariogenicity and low digestibility.

307 Characterization of Amylolytic Activities of Tulip Bulb Scales

Amylolytic activities extracted from scales of tulip (Tulipa gesneriana L. cv. Apeldoorn) bulbs stored at 4 °C for 6 weeks under moist conditions were characterized. Anion exchange chromatography of enzyme extract on DEAE-Sephacel revealed three peaks of amylolytic activity. Three enzymes showed different electrophoretic mobilties on nondenaturing polyacrylamide gels. The most abundant amylase activity was purified extensively with phenyl-agarose chromatography, gel filtration on Sephacryl S-200, and chromatofocusing on polybuffer exchanger PBE 94. The purified amylase was determined to be an endoamylase based on substrate specificity and end product analysis. The enzyme had a pH optimum of 6.0 and a temperature optimum of 55 °C when soluble starch was used as the substrate. The apparent Km value for soluble starch was 1.28 mg/ml. The inclusion of 2 mM CaCl2 in the reaction mixture resulted in a 1.4-fold increase in the enzyme activity. The presence of calcium ions also enhanced the thermo-stability of the enzyme at higher temperatures. The enzyme was able to hydrolyze soluble starch, amylose, amylopectin, and beta-limit dextrin, but it had no activity against pullulan, inulin, maltose, or p-nitrophenyl alpha-glucopyranoside. Only maltooligosaccharides, having a degree of polymerization of 7 or more, were hydrolyzed to a significant extent by the enzyme. Exhaustive hydrolysis of soluble starch with the enzyme yielded a mixture of maltose and matlooligosaccharides. This amylase activity was not inhibited by alpha- or beta-cyclodextrin upto a concentration of 10 mM. Maltose at a 50 mM concentration partially inhibited the enzyme activity, whereas glucose had no effect at that concentration.

PREVENTION OF ETHANOL-INDUCED GASTRIC LESIONS IN RATS BY NATURAL HONEY AND GLUCOSE–FRUCTOSE–SUCROSE–MALTOSE MIXTURE

The cytoprotective properties of various natural honey specimens and of a glucose–fructose–sucrose–maltose mixture (GFSM) against gastric ethanol-induced lesions have been evaluated in rats. GFSM mixture and honey (2.5 g kg−1) were given orally 30 min before administration of 100% ethanol (5 ml kg−1) for a further 15-min period. Animal pretreatment with GFSM or honey prevented the formation of gastric lesions. The number and severity of haemorrhagic lesions were reduced by 98%. Stomach acid content increased by 110–703% according to honey specimens. The similar protective effects of honey and GFSM mixture suggest that carbohydrates at high concentrations behave as mild irritants that can induce adaptive cytoprotection.

Somatic embryo maturation and plant regeneration in Abies nordmanniana Lk

The effect of maltose and sucrose at 1, 3 or 6% (w/v) on maturation of somatic embryos of the conifer Abies nordmanniana was studied in five different cell lines. At all concentrations tested, maltose was superior to sucrose in terms of the number of mature somatic embryos formed as well as their germination percentage. Optinum maltose concentrations varied between 3.4 and 4.3% based on quadratic regression analysis. Mixtures of maltose and sucrose were not found to produce as good results as pure maltose. The addition of polyethylene glycol-4000 (PEG-4000) to medium with 3% maltose further increased the yield of somatic embryos. The promotive effect of PEG-4000 was mainly exerted during the formation precotyledonary embryos. Germinated plants were hardened, established in soil and they resumed growth the following spring.

Production of Branched Cyclodextrins by Reverse Reaction of Microbial Debranching Enzymes

AbstractFormation of maltosyl cyclodextrins from mixtures of maltose and cyclodextrins by reverse reactions of Flavobacterium isoamylase and Klebsiella pullulanase was experimented and it was found that Klebsiella pullulanase produced 50.4mg maltosyl α‐cyclodextrin, 35.0mg maltosyl β‐cyclodextrin and 55.4mg maltosyl γ‐cyclodextrin per ml of reaction mixture, whereas Flavobacterium isoamylase did not form maltosyl cyclodextrins. Optimum conditions for formation of maltosyl β‐cyclodextrin by Klebsiella pullulanase were pH 4, 50°C reaction temperature and proportion of substrate 100mg β‐cyclodextrin/600mg maltose per ml.

Modelling of ethanol production by Saccharomyces cerevisiae from a glucose and maltose mixture

A model for ethanol production from a glucose-maltose mixture has been proposed, which includes a term representing the glucose repression effect on maltose consumption. The model parameters were estimated from batch experimental data. Results of sensitivity analysis on the Monod constants for glucose and maltose, and the repression constant, showed that ±10% changes in these three parameters caused no significant effect on data fitting.

IR and13C NMR Studiesc of Anomeric Mixtures of Maltose

Abstract Scrutiny of IR spectra of the anomeric mixtures of maltose has disclosed that α− and β−maltose, 1 and 2, exhibit characteristic absorption bands at 750±10 and 910±10 cm−1 respectively. The intensity ratio of vibration peaks at 850±110 and 780±0 cm−1 grows up to 1.05 with the proportional increments of 1. These are of utility in the qualitative assessment of the anomeric composition of maltose. Furthermore, a 13C NMR method for quantifying 1 and 2 was established on a thorough investigation including solvent selection, spin-lattice relaxation time (T1) determination, NOE suppressing, and the dependence of the accuracy on concentration and time. This method is convenient, accurate, and much quicker when compared to the previous methods.

α-Glucosidase synthesis in batch and continuous culture ofSaccharomyces cerevisiae

Glucose prevents maltose utilization bySaccharomyces cerevisiae in batch culture, whereas in a mixed carbohydrate-limited chemostat, maltose and glucose were consumed simultaneously. The specific activity of α-glucosidase was dependent on the dilution rate as well as the proportion of maltose in the mixture. Maximum specific activities in the batch and chemostat cultures on mixtures of maltose and glucose were lower than corresponding values observed on maltose alone.

Specific maltose labeling in the reducing glucose moiety

Radioactive maltose with label in the reducing glucose moiety was prepared using a glucosyltransferase enzyme to catalyze exchange of [6- 3H]glucose into unlabeled maltose. The enzyme was isolated from spinach by ammonium sulfate precipitation followed by DEAE column chromatography. A 77% yield of [6- 3H]maltose was obtained after a reaction of 100 nmol of maltose with 0.0147 nmol of [6- 3H]glucose was catalyzed by the most active column peak. The product was exclusively labeled in the reducing glucose moiety as indicated by the label occurring only in sorbitol following sodium borohydride reduction and sulfuric acid hydrolysis. Between 88.3 and 96.0% of the tritium in the synthesized preparation was present as [6- 3H]maltose by Dowex 1-X4 chromatography. This column separates [6- 3H]maltose-[U- 14C]maltose mixtures and [6- 3H]glucose-[U- 14C]glucose mixtures apparently as a result of an isotope effect.

The coulometric determination of maltose with maltase

Maltose is commonly determined along with other reducing sugars in the classical saccharogenic procedures. In the proposed method maltase, an enzyme which hydrolyzes α-D-glucosides, is employed to hydrolyze maltose to glucose. The maltase is coupled with glucose oxidase which converts glucose to gluconic acid and hydrogen peroxide. The peroxide which is produced oxidizes iodide to iodine in the presence of molybdenum(VI). Iodine reacts with an excess of thiosulfate which is subsequently determined by titration with generated iodine. Concentrations of maltose between 50 and 400 mg % may be determined in a sample size of 50 μl. Accuracy and precision are comparable to spectrophotometric procedures for maltose. A mixture of maltose and glucose may be determined using two enzyme preparations, but a considerably more complex procedure is required and results may be affected by the relative amount of glucose present.

Kinetics and Mechanism of Transfer Action of Saccharifying α-Amylase of Bacillus subtilis

1. The formation of phenol (φ) was observed in the mixture of maltose (M) and phenyl α-glucoside (φG), which was catalyzed by saccharifying α-amylase (EC 3. 2. 1. 1) of Bacillus subtilis, although φG itself was not hydrolyzed either in the presence or absence of glucose. Thin layer chromatography (TLC) of the reaction mixture revealed the formation of a small amount of phenyl α-maltoside (φM). From these results, it was concluded that φM was produced from M and φG by glucosyl transfer catalyzed by the enzyme, and then φM was hydrolyzed into φ and M. Since the overall rate of formation of phenol, vφ, is limited by the rate of transfer, vr, the latter can be obtained directory from the measurement of the former. This system was utilized for studying the kinetics of transfer action of this enzyme. 2. The rate of transfer as a function of φG concentration at a fixed concentration of M proceeded according to the Michaelis-Menten kinetics within the range of concentrations of φG examined, and the apparent Michaelis constant KmφG for φG was 250 mM at a maltose concentration of 42 mM. On the other hand, the rate of transfer, vr, as a function of the concentration of M in a fixed concentration of φG showed a remarkable sigmoidal shape in the region of lower substrate concentrations and showed a maximum at around 100 mM, above which it decreased hyperbolically. 3. The ratio between the rate of transfer, vT, and that of hydrolysis of maltose, vW, vT/vW increased with the concentration of φG, showing that the hydrolysis of M is inhibited by φG. 4. Methyl alcohol was found to serve as an acceptor, judging from the formation of methyl α-glucoside detected by TLC. 5. The hydrolysis of M, and the transfer action of a glucosyl residue of M to φG and to M were explained by assuming essentially the same mechanism as that previously proposed for the hydrolysis of φM.

Comparative Biochemical Studies of ^|^alpha;-Glucosidases

The properties of brewer's yeast α-glucosidase have been investigated. The enzyme was capable of hydrolyzing various α-glucosides and was active especially on aryl-α-glucosides in comparison with other α-glucosides and sugars. The rate of hydrolysis decreased in following order: phenyl-α-glucosides, sucrose, matlose and isomaltose.The range of opt. temp. was 40-45°C and opt. pH, 6.5-7.0.Cu++and Hg++inhibited strongly the enzyme activity and Zn++, moderately. The enzyme was suggested to be a sulfhydryl enzyme from the inhibition experiments by SH-reagents and the effects of glutathione on the activity.The enzyme synthesized some oligosaccharides from maltose. As the transglucosidation products, nigerose, isomaltose, kojibiose and maltotriose were detected by paperchromatography.Pure nigerosc was separated by splitting maltose with amyloglucosidase from the mixture of maltose and nigerose and by use of successive carbon column chromatography.

Significance of Oligosaccharide Intermediates in Dextran Synthesis

THE recent isolation1 of O-α-D-glucopyranosyl-(1→6)-O-α-D-glucopyranosyl-(1→2) β-D-fructofuranoside (1) from a complex mixture of oligosaccharides produced by the action of a cell-free extract of Aspergillus niger ‘152’ on a sucrose–maltose mixture prompted us to examine its role in dextran synthesis, since the first step in the synthesis of dextran could be: