scholarly journals The mechanism of biosynthesis and direction of chain extension of a polyl-(N-acetylglucosamine 1-phosphate) from the walls of Staphylococcus lactis N.C.T.C. 2102

1969 ◽  
Vol 113 (4) ◽  
pp. 635-642 ◽  
Author(s):  
D. Brooks ◽  
J Baddiley
Keyword(s):  
Enzyme System ◽  
Group Analysis ◽  
Chain Extension ◽  
Pulse Labelling ◽  
Uridine Diphosphate ◽  
High Concentration ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
End Group

1. The synthesis of a polymer of N-acetylglucosamine 1-phosphate, occurring in the walls of Staphylococcus lactis N.C.T.C. 2102, was examined by using cell-free enzyme preparations. The enzyme system was particulate, and probably represents fragmented cytoplasmic membrane. 2. Uridine diphosphate N-acetylglucosamine was the only substrate required for polymer synthesis and labelled substrate was used to show that N-acetylglucosamine 1-phosphate is transferred as an intact unit from substrate to polymer. 3. The properties of the enzyme system were studied. A high concentration of Mg2+ or Mn2+ was required for optimum activity, and the pH optimum was about 8·5. 4. End-group analysis during synthesis in vitro showed that newly formed chains contain up to about 15 repeating units. Pulse-labelling indicated that chain extension occurs by transfer from the nucleotide to the ‘sugar-end’ of the chain, i.e. to the end that is not attached to peptidoglycan in the wall.

scholarly journals Pre-fermentative treatment of a model wine with aim to serve as a functional food with decreased alcohol content

2017 ◽  
Vol 63 (01) ◽  
pp. 47-53
Author(s):  
Irina Mladenoska ◽  
Verica Petkova ◽  
Tatjana Kadifkova Panovska
Keyword(s):  
Enzyme Activity ◽  
Gluconic Acid ◽  
Functional Food ◽  
Ph Value ◽  
Enzymatic Reaction ◽  
Alginate Beads ◽  
High Concentration ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
Initial Ph

The effect of substrate concentration on the enzyme activity in the reaction of glucose conversion into gluconic acid was investigated by using three different enzyme preparations in media with two different glucose concentrations. The media were simulating the conditions in the must, thus named as minimal model must, and were composed form combination of several organic acids and glucose. Those media were having initial pH of 3.5 that is a very unfavorable for glucose oxidase activity having a pH optimum at the pH value of 5.5. Among the three preparations used, the bakery additive, Alphamalt Gloxy 5080, was the most active in the medium with glucose concentration of 10 g/L, showing conversion of more than 70% for the period of 24 h, while the same enzyme preparation in the medium with 100 g/L glucose converted only about 7% of glucose. The pH value of the medium at the beginning and at the end of the enzymatic reaction was a good indicator of the enzyme activity. It seems that for the conversion of glucose in higher concentration, enzymatic preparation in high concentration should also be used. The preliminary attempt of immobilization of two preparations of glucose oxidases in alginate beads was also performed and a successful immobilization procedure for utilization in food industry was preliminarily developed. Keywords: glucose oxidases, enzymatic pretreatment, glucose, gluconic acid, model wine, functional food

Conversion of Flavanone to Flavone, Dihydroflavonol and Flavonol with an Enzyme System from Cell Cultures of Parsley

1981 ◽  
Vol 36 (9-10) ◽  
pp. 742-750 ◽  
Author(s):  
L. Britsch ◽  
W. Heller ◽  
H. Grisebach
Keyword(s):  
Microsomal Fraction ◽  
Specific Activity ◽  
Enzyme System ◽  
High Specific Activity ◽  
Cell Suspension Cultures ◽  
Soluble Enzyme ◽  
Enzyme Preparations ◽  
Malonyl Coa ◽  
In Vitro Biosynthesis

Abstract Soluble enzyme preparations from irradiated cell suspension cultures of parsley (Petroselinum hortense Hoffm.) catalyse the conversion of flavanone to flavone, dihydroflavonol and flavonol. These reactions require 2-oxoglutarate, Fe2+ and ascorbate as cofactors. In the presence of these cofactors conversion of dihydroflavonol to flavonol was also observed. With this system in vitro biosynthesis of radioactive flavone, dihydroflavonol and flavonol from [2-14C]malonyl-CoA and 4-coumaroyl-CoA in good yield and with high specific activity is possible.We postulate that synthesis of flavone and flavonol from flavanone proceeds via 2-hydroxy-and 2,3-dihydroxyflavanone, respectively, with subsequent dehydration.The microsomal fraction of the parsley cells contains an NADPH-dependent flavanone 3'-hydroxylase.

The Enzymic Phosphorylation of N6-(Δ2-Isopentenyl)adenosine in Chick Liver Homogenates

1973 ◽  
Vol 51 (10) ◽  
pp. 1341-1346 ◽  
Author(s):  
B. D. McLennan ◽  
A. Pater
Keyword(s):  
Biological Effects ◽  
Adenosine Kinase ◽  
Side Chain ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
Liver And Kidney ◽  
Isopentenyl Adenosine ◽  
Modified Nucleoside ◽  
Chick Tissue

Enzyme preparations from chick kidney and liver rapidly phosphorylate the modified nucleoside, N6-(Δ2-isopentenyl) adenosine. The resulting metabolite behaves electrophoretically as a mononucleotide and is quantitatively hydrolyzed to the nucleoside by 5′-nucleotidase. The isopentenyl side chain is not altered in the phosphorylated derivative. It is concluded that the metabolite is N6-(Δ2-isopentenyl) adenosine-5′-monophosphate. The properties of the enzyme activity responsible for the phosphorylation resemble the properties of adenosine kinase isolated from sarcoma-180 cells, and from rabbit liver, with respect to pH optimum, Km value, and sensitivity to magnesium ion and ATP. Thus, it seems probable that the phosphorylation observed in the chick tissue preparations is due to adenosine kinase. The mononucleotide could not be further phosphorylated in vitro by adenylate kinase. This observation, coupled with the fact that isopentenyladenosine is biosynthesized at the macromolecular level, suggests that the 5′-monophosphate ester may be the form through which some of the biological effects of this modified nucleoside are manifested.A major end product of N6-(Δ2-isopentenyl) adenosine catabolism in chick liver and kidney homogenates is uric acid.

scholarly journals End group analysis of naturally terminated and UV lesion terminated T7 in vitro RNA

1976 ◽  
Vol 3 (12) ◽  
pp. 3359-3368
Author(s):  
R. Ali ◽  
R. Millette ◽  
W. Sauerbier
Keyword(s):  
Group Analysis ◽  
End Group

scholarly journals Teichoic acid synthesis in Bacillus stearothermophilus

1974 ◽  
Vol 138 (3) ◽  
pp. 525-535 ◽  
Author(s):  
L. D. Kennedy
Keyword(s):  
Alkaline Hydrolysis ◽  
Bacillus Stearothermophilus ◽  
De Novo ◽  
Enzyme System ◽  
Teichoic Acid ◽  
Periodate Oxidation ◽  
Acid Synthesis ◽  
Pulse Labelling ◽  
Glycerol Phosphate ◽  
Enzyme Preparations

1. Particulate enzyme preparations obtained from Bacillus stearothermophilus B65 by digestion with lysozyme were shown to catalyse teichoic acid synthesis. With CDP-glycerol as sole substrate the preparations synthesized 1,3-poly(glycerol phosphate). It was characterized by alkaline hydrolysis, by glucosylation to the alkali-stable 2-glucosyl-1,3-poly(glycerol phosphate) with excess of UDP-glucose and a Bacillus subtilis Marburg enzyme system, by degradation of this latter product with 60%HF and periodate oxidation of the resulting glucosylglycerol. The specificity of the B. subtilis system previously reported (Glaser & Burger, 1964), was confirmed in the present work. 2. Pulse-labelling experiments, followed by periodate oxidation of the product and isolation of formaldehyde from the glycerol terminus of the polymer, showed that the B. stearothermophilus enzyme system transferred glycerol phosphate units to the glycerol end of the chain. The transfer reaction was irreversible. It was not determined if these poly(glycerol phosphate) chains were synthesized de novo, but it was shown that the newly synthesized oligomers were bound to much larger molecules. 3. When the B. stearothermophilus enzyme system was supplied with both CDP-glycerol and UDP-glucose, 1-glucosyl-2,3-poly(glycerol phosphate) was synthesized in addition to the 1,3-isomer. The former polymer was characterized by acid and alkaline hydrolysis, degradation with HF and periodate oxidation of the resulting glucosylglycerol, and periodate oxidation of the intact polymer followed by mild acid hydrolysis. This latter procedure removed the glucose substituents without disrupting the poly(glycerol phosphate) chain. 4. The poly(glycerol phosphate) isomers were distinguished by glucosylation with the B. subtilis enzymes and alkaline hydrolysis, the 2,3-isomer remaining alkali-labile. The proportion of 2,3-poly(glycerol phosphate) in the product increased with increasing amounts of UDP-glucose in the incubation mixture, but the total glycerol phosphate incorporated into products remained constant. It is suggested that the synthetic pathways of the two poly(glycerol phosphate) species may share a rate-limiting step.

scholarly journals Comparison in different species of biliary bilirubin-IX α conjugates with the activities of hepatic and renal bilirubin-IX α-uridine diphosphate glycosyltransferases

1977 ◽  
Vol 164 (3) ◽  
pp. 737-746 ◽  
Author(s):  
J Fevery ◽  
M Van de Vijver ◽  
R Michiels ◽  
K P M Heirwegh
Keyword(s):  
Glucuronic Acid ◽  
Mammalian Species ◽  
Liver Homogenate ◽  
Species Variation ◽  
Bile Pigment ◽  
Uridine Diphosphate ◽  
Ph Optimum ◽  
Equal Importance ◽  
Liver And Kidney

The bilrubin-IXalpha conjugates in bile and the activities of bilirubin-IX alphax–UDP-glycosyltransferases in liver and kidney were determined for ten species of mammals and for the chicken. 1. In the mammalian species, bilirubin-IX alpha glucuronide was the predominant bile pigment. Excretion of neutral glycosides was unimportant, except in the cat, the mouse, the rabbit and the dog, where glucose and xylose represented 12–41% of total conjugating groups bound to bilirubin-IX alpha. In chicken bile, glucoside and glucuronide conjugates were of equal importance. They probably represent only a small fraction of the total bile pigment. 2. The transferase activities in liver showed pronounced species variation. This was also apparent with regard to activation by digitonin, pH optimum and relative activities of transferases acting on either UDP-glucuronic acid or neutral UDP-sugars. 3. Man, the dog, the cat and the rat excrete bilirubin-IX alpha largely as diconjugated derivatives. In general, diconjugated bilirubin-IX alpha could also be synthesized in vitro with liver homogenate, bilirubin-IX alpha and UDP-sugar. In contrast, for the other species examined, bilirubin pigments consisted predominantly of monoconjugated bilirubin-IX alpha. Synthesis in vitro with UDP-glucuronic acid, UDP-glucose or UDP-xylose as the sugar donor led exclusively to the formation of monoconjugated bilirubin-IX alpha. 4. The transferase activities in the kidney were restricted to the cortex and were important only for the rat and the dog. No activity at all could be detected for several species, including man. 5. Comparison of the transferase activities in liver with reported values of the maximal rate of excretion in bile suggests a close linkage between conjugation and biliary secretion of bilirubin-IX alpha.

scholarly journals Sodium plus Potassium-Activated, Ouabain-Inhibited AdenosineTriphosphatase from a Fraction of Rat Skeletal Muscle, and Lack of Insulin Effect on It

1969 ◽  
Vol 54 (2) ◽  
pp. 188-202 ◽  
Author(s):  
Ellen Rogus ◽  
Thomas Price ◽  
Kenneth L. Zierler
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Enzyme System ◽  
Human Muscle ◽  
Rat Skeletal Muscle ◽  
Ph Optimum ◽  
Insulin Effect ◽  
Na Efflux

An ATPase, activated by Na+ plus K+ in the presence of Mg++ and inhibited by ouabain, has been obtained from rat skeletal muscle. Unlike ATPase's with similar properties obtained from other preparations, this ATPase was found only in the fraction containing fragmented sarcoplasmic reticulum. It is suggested that in rat skeletal muscle this ATPase may reside in sarcoplasmic reticulum and not in sarcolemma. This ATPase differed in its pH optimum and in its cation sensitivity from that of rat brain and from that of human muscle reported by Samaha and Gergely (1965, 1966). Because insulin accelerates Na+ efflux from muscle, efforts were made to determine whether or not this effect of insulin could be attributed to increased Na+ + K+-activated ATPase activity. Insulin, administered either in vivo or in vitro, had no demonstrable effect on the enzyme system, nor did it protect against inhibition by ouabain.

Synthesis of β-glucans by Bradyrhizobium japonicum and Rhizobium fredii

1992 ◽  
Vol 38 (6) ◽  
pp. 510-514 ◽  
Author(s):  
Arvind A. Bhagwat ◽  
Donald L. Keister
Keyword(s):  
Molecular Weight ◽  
Nitrogen Fixation ◽  
Membrane Protein ◽  
Bradyrhizobium Japonicum ◽  
Rhizobium Meliloti ◽  
Uridine Diphosphate ◽  
Enzyme Preparations ◽  
Rhizobium Fredii ◽  
Diphosphate Glucose

Particulate enzyme preparations from Rhizobium and Bradyrhizobium synthesize β-glucans when incubated with uridine diphosphate glucose (UDP-glucose) and a divalent cation. Synthesis of β-1,2-linked glucans in Rhizobium fredii involves the product of the ndvB gene, a 319-kDa membrane protein, which is labeled with [14C]glucose from UDP-[14C]glucose as previously demonstrated in Rhizobium meliloti and Agrobacterium sp. Bradyrhizobium japonicum synthesize β-1,3- and β-1,6-linked glucans of a lower molecular weight than those synthesized by R. meliloti. In comparative experiments, no evidence was found for a protein-bound intermediate in B. japonicum. The ndvB gene of R. fredii was mobilized to B. japonicum and the gene was expressed, as evidenced by appearance of a large membrane protein (ca. 319 kDa) which was labeled with UDP-[14C]glucose in vitro. Key words: soybean, nitrogen fixation, β-glucan, Bradyrhizobium, Rhizobium.

The isolation of poly-α-L-glutamic acid from the oviduct of the domestic fowl

1966 ◽  
Vol 166 (1004) ◽  
pp. 341-357 ◽  
Keyword(s):  
Molecular Weight ◽  
Glutamic Acid ◽  
Domestic Fowl ◽  
Group Analysis ◽  
The Body ◽  
Specific Viscosity ◽  
Immunological Specificity ◽  
End Group

These investigations were carried out with the object of isolating from specific regions of the oviduct of the domestic fowl substances which might be effective in prolonging the survival of avian sperm in vitro . Poly- α -L-glutamic acid has been isolated from the infundibulum, upper magnum and utero-vaginal junction of oviducts from domestic fowls in full lay. The molecular weight was found to be 73 600 by specific viscosity and 81 500 as determined by end group analysis. The structure was proved by quantitative determination of glutamic acid in hydrolysates of the purified material, by establishing the L-configuration of the glutamic acid so produced, by comparison of the infra red spectrum of the product with those of synthetic poly- α -L-glutamate, and with bacterial poly- γ -DL-glutamate, and by the immunological specificity of antiserum prepared in rabbits to the purified natural product. Poly- α -L-glutamic acid was found to preserve the motility of cock sperm for several hours in vitro at the body temperature of the fowl. This effect appears to be specific to Poly- α -L-glutamic acid and is also dependent partly upon the molecular weight of the polyglutamates.

FERMENTATIVE HYDROLYTIC PREPARATION METHODS OF CEREAL WORT FOR ALCOHOL FERMENTATION

1970 ◽  
pp. 52-56
Author(s):  
Е. M. Serba ◽  
М. B. Overchenko ◽  
L. V. Rimareva ◽  
N. I. Ignatova ◽  
А. E. Orekhova ◽  
...  
Keyword(s):  
Alcoholic Fermentation ◽  
Raw Materials ◽  
Alcohol Concentration ◽  
Activity Level ◽  
Optimal Dosage ◽  
Main Role ◽  
Alcohol Fermentation ◽  
Ph Optimum ◽  
Amylolytic Enzyme ◽  
Enzyme Preparations

In the production of alcohol in the preparation of grain raw materials for fermentation, the main role is given to enzyme preparations of amylolytic action, which are key enzymes that catalyze the hydrolysis of starch. Amylolytic enzyme preparations with a different composition of enzymes and their level of activity, a mechanism of biocatalytic effect on starch, and a range of thermal and pH optimum are widely represented on the Russian market. The development of optimal conditions for the preparation of grain wort, the rational selection and dosage of concentrated enzyme preparations, the properties of which correspond to the parameters of the technological process, will ensure the effective preparation of starch for fermentation, and increase the profitability of alcohol production. The aim of this work was to study the influence of enzyme preparations of amylolytic action and the conditions of their use on the efficiency of the process of alcoholic fermentation and the yield of the final product, ethanol. The effect of various dosages of enzyme preparations of glucoamylase action, with a different ratio of the main enzyme glucoamylase and minor enzyme α-amylase, as well as methods for preparing wheat wort on the process of alcoholic fermentation, was studied. It was found that the enzyme preparation, the source of glucoamylase, in which α-amylase was present in a ratio of 15: 1 (in terms of activity level), turned out to be more effective in fermenting prepared wheat wort: its optimal dosage was 8 units. GLS / g starch. The presence of a sufficient amount of α-amylase in this preparation compensated for the dosage of thermostable α-amylase. The alcohol concentration in the mash was 10.2% vol., The alcohol yield was 67.9 cm3 / 100 g of starch. When glucoamylase with a lower ratio of the main and minor enzyme (75: 1) was used at the saccharification stage, an increase in the wort fermentation depth was observed with an increase in the concentration of glucoamylase to 9-10 units of GLS / g and α-amylase to 0.5 units. AC / g. It was also found that an increase in the duration of enzymatic-hydrolytic preparation of the wort had a positive effect on the fermentation process, the alcohol concentration in the mash increased to 10.2 vol.%. It was shown that the introduction of proteases into the wort helps to reduce the viscosity of grain wort, enriching it with assimilable yeast amino acids, which leads to an increase in the yield of alcohol. It has been confirmed that the synergy of the action of enzymes of amylolytic and proteolytic effects on polymers of grain raw materials allows to increase the efficiency of their conversion to ethanol. The conditions of enzymatic-hydrolytic processing of grain raw materials for fermentation are developed. The use of the digestion stage did not significantly affect the fermentation results of wheat wort.

Sign in / Sign up

Export Citation Format

Share Document