scholarly journals Chemoenzymatic synthesis of 3-ethyl-2,5-dimethylpyrazine by L-threonine 3-dehydrogenase and 2-amino-3-ketobutyrate CoA ligase/L-threonine aldolase

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tomoharu Motoyama ◽  
Shogo Nakano ◽  
Fumihito Hasebe ◽  
Ryo Miyata ◽  
Shigenori Kumazawa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Chemical Reactions ◽  
Maillard Reaction ◽  
Condensation Reaction ◽  
Chemoenzymatic Synthesis ◽  
Moderate Reaction ◽  
Threonine Aldolase ◽  
Coa Ligase ◽  
Low Concentrations ◽  
Aldolase Activity

AbstractPyrazines are typically formed from amino acids and sugars in chemical reactions such as the Maillard reaction. In this study, we demonstrate that 3-ethyl-2,5-dimethylpyrazine can be produced from L-Thr by a simple bacterial operon. We conclude that EDMP is synthesized chemoenzymatically from L-Thr via the condensation reaction of two molecules of aminoacetone and one molecule of acetaldehyde. Aminoacetone is supplied by L-threonine 3-dehydrogenase using L-Thr as a substrate via 2-amino-3-ketobutyrate. Acetaldehyde is supplied by 2-amino-3-ketobutyrate CoA ligase bearing threonine aldolase activity from L-Thr when CoA was at low concentrations. Considering the rate of EDMP production, the reaction intermediate is stable for a certain time, and moderate reaction temperature is important for the synthesis of EDMP. When the precursor was supplied from L-Thr by these enzymes, the yield of EDMP was increased up to 20.2%. Furthermore, we demonstrate that this reaction is useful for synthesizing various alkylpyrazines.

scholarly journals Metabolic homoeostasis of l-threonine in the normally-fed rat. Importance of liver threonine dehydrogenase activity

1983 ◽  
Vol 214 (3) ◽  
pp. 687-694 ◽  
Author(s):  
M I Bird ◽  
P B Nunn
Keyword(s):  
Dehydrogenase Activity ◽  
High Protein Diet ◽  
Fed State ◽  
Threonine Dehydratase ◽  
Threonine Dehydrogenase ◽  
Threonine Aldolase ◽  
Coa Ligase ◽  
Metabolic States ◽  
Aldolase Activity

Threonine dehydratase, threonine aldolase and threonine dehydrogenase activities were assayed in livers of rats that had been normally-fed, starved for 72 h, fed a high-protein diet or normally-fed and injected with glucagon or cortisone. A modified continuous spectrophotometric assay for threonine aldolase overcame interference resulting from threonine dehydratase activity and revealed that threonine aldolase activity was very low in rat liver, irrespective of the metabolic state of the animal. The concentration of free threonine was determined in livers of animals subjected to the same treatments as described above. Using Michaelis-Menten kinetics to estimate enzyme activities in vivo at intracellular threonine concentrations it was calculated that in the normally-fed state, 87% of the threonine degraded was catabolized by threonine dehydrogenase. In other metabolic states (except in glucagon-treated animals) threonine dehydratase was the major enzyme catalysing threonine catabolism. It was concluded that threonine dehydrogenase activity plays a hitherto unrecognized role in the metabolic homoeostasis of threonine in the normally-fed rat and that this enzyme activity, in association with 2-amino-3-oxobutyrate CoA-ligase, accounts for the known rate of glycine formation from threonine in the rat.

Multiplication of a Klebsiella pneumoniae Strain in Water at Low Concentrations of Substrates

1988 ◽  
Vol 20 (11-12) ◽  
pp. 117-123 ◽  
Author(s):  
D. van der Kooij ◽  
W. A. M. Hijnen
Keyword(s):  
Amino Acids ◽  
Water Treatment ◽  
Klebsiella Pneumoniae ◽  
Substrate Concentration ◽  
Treatment System ◽  
Water Treatment System ◽  
Low Concentrations ◽  
Ks Values ◽  
Substrate Concentrations

A K.pneumoniae strain, isolated from a water treatment system, was tested in growth measurements for its ability to multiply at substrate concentrations of a few micrograms per liter. The organism multiplied on mixtures of carbohydrates and amino acids at a substrate concentration of 1 µg of C of each compound per liter. Tests with individual compounds revealed that especially carbohydrates were utilized at low concentrations. The Ks values obtained for maltose and maltopentaose were 53 µg of C/l and 114 µg of C per liter, respectively. The significance of the growth of K.pneumoniae at low substrate concentrations is discussed.

scholarly journals Effect of free amino acids and peptide hydrolysates from sunflower seed protein on the formation of pyrazines under different heating conditions

RSC Advances ◽  
2021 ◽  
Vol 11 (45) ◽  
pp. 27772-27781
Author(s):  
Furong Wang ◽  
Hailiang Shen ◽  
Xi Yang ◽  
Ting Liu ◽  
Yali Yang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Maillard Reaction ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sunflower Seed ◽  
Seed Protein ◽  
Heating Temperature ◽  
Reaction Model

Exploring the effect of heating temperature and time on the formation of pyrazines; revealing the potential roles of FAAs and hydrolyzed sunflower seed peptides in the Maillard reaction model.

Sodium borohydride: A versatile reagent in the reductive N-monoalkylation of α-amino acids and α-amino methyl esters

2002 ◽  
Vol 80 (7) ◽  
pp. 779-788 ◽  
Author(s):  
Giancarlo Verardo ◽  
Paola Geatti ◽  
Elena Pol ◽  
Angelo G Giumanini
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sodium Borohydride ◽  
Carbonyl Compounds ◽  
Condensation Reaction ◽  
Methyl Esters ◽  
Reducing Agent ◽  
Reductive Condensation ◽  
Versatile Reagent

α-Amino acids and α-amino methyl esters are easily converted to their N-monoalkyl derivatives by a reductive condensation reaction using several carbonyl compounds in the presence of sodium borohydride. This reducing agent has shown a wide versatility with minor but essential procedural variations. The reaction allows the α-monodeuterium labeling of the new N-substituent by use of sodium borodeuteride.Key words: α-amino acid, α-amino methyl esters, sodium borohydride, reductive N-monoalkylation, carbonyl compounds.

scholarly journals Chemical Reactions of Amino Acids with Aldehydes. Part VI

1961 ◽  
Vol 35 (11) ◽  
pp. 1027-1029
Author(s):  
Sakae EMOTO ◽  
Makoto ANDO
Keyword(s):  
Amino Acids ◽  
Chemical Reactions

ChemInform Abstract: L-Threonine Aldolase in Organic Synthesis: Preparation of Novel β- Hydroxy-α-amino Acids.

ChemInform ◽  
2010 ◽  
Vol 26 (46) ◽  
pp. no-no
Author(s):  
V. P. VASSILEV ◽  
T. UCHIYAMA ◽  
T. KAJIMOTO ◽  
C.-H. WONG
Keyword(s):  
Amino Acids ◽  
Organic Synthesis ◽  
Threonine Aldolase

Chemically Selective Reactions in Confined Spaces in Hybrid Aerogels

2005 ◽  
Vol 899 ◽  
Author(s):  
Xipeng Liu ◽  
Chunhua Yao ◽  
William M Risen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Metal Ions ◽  
Chemical Reactions ◽  
Reaction Products ◽  
Spatial Confinement ◽  
Confined Spaces ◽  
Hybrid Silica ◽  
Hybrid Aerogels ◽  
Chemically Selective

AbstractBy employing novel hybrid silica/functional polymer aerogels, control of the course of chemical reactions between reactants confined inside of the aerogels with reactants whose access to the confinement domain is controlled by diffusion has been explored. Thus, monolithic silica/biopolymer hybrid aerogels have been synthesized with coordinated metal ions that can react with amino acids, such as L-cysteine, that are provided externally in a surrounding solution. Metal ions, such as Au(III), that can react in solution with the amino acid to produce one set of products under a given set of stoichiometric or concentration conditions, and a different set of products under a second set of conditions, were selected for incorporation into the aerogel. It was discovered that the course of the reaction can be changed by spatial confinement of the reaction domain in the aerogel. For example, in the case of Au(III) and L-cysteine, the Au(III) ions are confined in nanoscale domains, and when they are reacted with the amino acid, the nature of the reaction products is controlled by diffusion of the L-cysteine into the domains. Exploration of these and related phenomena will be presented.

Calcium-binding proteins in a vorticellid contractile organelle

1975 ◽  
Vol 19 (1) ◽  
pp. 203-213
Author(s):  
W.B. Amos ◽  
L.M. Routledge ◽  
F.F. Yew
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Sodium Dodecyl ◽  
Aromatic Amino Acids ◽  
Calcium Binding Proteins ◽  
Polyacrylamide Gels ◽  
Protein Species ◽  
Low Concentrations

The proteins of the contractile spasmoneme of Zoothamnium have been examined for comparison with other motile systems. Though capable of calcium-induced contraction, glycerinated preparations of the spasmoneme contain neither actin nor tubulin at levels that can be detected in polyacrylamide gels. Sixty per cent of the protein in sodium dodecyl sulphate gels migrates in a band at a molecular weight of approximately 20,000, consisting largely of 2 similar protein species which are here given the name of spasmins. The amino acid composition of 2 spasmin fractions has been determined by a fluorimetric method. They are rich in Asx, Glx and serine, but have few aromatic amino acids and no cystine or methionine. In calcium-buffered polyacrylamide gels, it was observed that a reduction in the electrophoretic mobility of the spasmins was induced specifically by calcium (but not magnesium) at the same low concentrations as induce contraction. This indicates that the spasmins are calcium-binding proteins which may be involved directly in the calcium-induced contraction of the spasmoneme.

scholarly journals Gel Formation in Low Concentrated Solutions of Glycyram and Amino Acids in the Presence of Silver Nitrate

2021 ◽  
Vol 7 (11) ◽  
pp. 11-21
Keyword(s):  
Amino Acids ◽  
Silver Nitrate ◽  
Food Industry ◽  
Silver Ions ◽  
Electrolyte Solutions ◽  
Low Molecular Weight ◽  
Gel Formation ◽  
Recent Past ◽  
Concentrated Solutions ◽  
Low Concentrations

Abstract. Research relevance: low molecular weight supramolecular hydrogels are unique objects that can solve many pressing problems in medicine, food industry and other sectors of the national economy. Research objectives: in recent past, it was discovered that low-concentration solutions of L-cysteine and silver nitrate (CSN) can form, when electrolyte solutions are added to hydrogels. We were faced with the task of obtaining hydrogels from dilute solutions of glycyram (GC) by adding CSN, since GC, due to its poor solubility, has low bioavailability. Materials and research methods: using the method of isomolar series, a comparative study of the formation of hydrogels by dilute GC solutions with the addition of CSN and GCP was carried out. It has been found that most durable hydrogels were obtained using CSN. Thus, GC hydrogels were obtained at a concentration of 10−3 M after adding CSN and GCP, which have a supramolecular character and combine the properties of GC, amino acids, and silver ions. Research results: glycyram hydrogels were obtained at its concentration equal to 10−3 M by mixing it with silver amino acids L-cysteine (CSN) and L-glutamic acid (GCP) solutions in same low concentrations. Conclusions: hydrogels with glycyram form silver solutions of those amino acids that are capable of giving frame structures at a ratio of amino acid: silver nitrate of 1.25.

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