Metagenomic analysis revealing the metabolic role of microbial communities in the free amino acid biosynthesis of Monascus rice vinegar during fermentation

Free amino acid(FAA)is the important component of vinegar that infl uences quality perception and consumer acceptance.FAA is one of the major metabolites produced by microorganisms;however,the microbial metabolic network on FAA biosynthesis remains unclear.Through metagenomic analysis,this work aimed to elucidate the roles of microbes in FAA biosynthesis during Monascus rice vinegar fermentation.Taxonomic profiles from functional analyses showed 14 dominant genera with high contributions to the metabolism pathways.The metabolic network for FAA biosynthesis was then constructed,and the microbial distribution in different metabolic pathways was illuminated.The results revealed that 5 functional genera were closely involved in FAA biosynthesis.This study illuminated the metabolic roles of microorganisms in FAA biosynthesis and provided crucial insights into the functional attributes of microbiota in vinegar fermentation.

Synthesis and Structure Analysis of a Tripeptide Containing N-methyl Group Amino Acid

A convenient method of synthesizing a tripeptide-containing N-methyl group amino acid was developed using O-benzotriazole-N,N,N＇,N＇-tetramethyluronium-hexafluorophosphate as the condensing agent. The crystals of tripeptide had white needles belonging to the orthorhombic space group P2_12_12_1. The conformational preference for homochiral tripeptides with one N-methylated amide bond was also investigated. Crystal-structure analysis showed that homochiral tripeptides with an internal N-methylated amide bond preferred a trans-amide form, thereby giving the peptide β-fold characteristics. Intermolecular C-H···O and N-H···O hydrogen bonds linked the molecules into a one-dimensional chain and stabilized the structure.

Synthesis of Macrocycles Containing Amino Acid Ester and Aryl-heterocyclic Units

Four kinds of new macrocycles containing amino acids and nyl-heterocyclic units were synthesized by the condensation of di-esters containing Ts-amino acids units with di-halogenated compounds at room temperature. The macrocycles were characterized by elemental analysis, IR,MS(FAB) and 1H NMR

STUDIES ON THE SYNTHESIS AND ANTITUMOR ACTIVITY OF AMINO ACID ESTER DERIVATIVES OF BENZISOSELENAZOLONE

This paper reports a simple method for the synthesis of amino acid ester derivatives of benzisoselenazolone.Their anticancer activity is also given.

SYNTHESIS OF NEW ESTRONE DERIVATIVES OF AMINO ACIDS AND PEPTIDES

A series of estrone derivatives of amino acids and peptides haze been synthesized by different coupling reagents and the binding affinity of deblocked derivatives to the estrogen receptor of rats uteri have been measured by a comptetive radiometric bind- ing assay.

The reactive activities of natural amino acids: key principles of peptide-templated Au cluster synthesis

Coating of gold nanoclusters with peptides is an important targeting method in biomedical applications.However, their synthetic method highly influences their targeting ability. Current methods often use harsh reagents and organic solvents to control morphology, which are not preferred for biomedical applications. Recently, several peptides with specific amino acid sequences have successfully been used to reduce Au ions and synthesize biocompatible peptide-covered gold particles in situ.However, the molecular mechanism of peptide-assisted nanocluster formation is yet unclear. Thus, reactive abilities of different amino acids should be studied to improve design of peptides with predetermined amino acid content and consequently, synthesize gold nanoclusters with improved performance. In this theoretical study, we have approximated the reactive abilities of 20 natural amino acids in their neutral state using density functional theory calculations, such as Fukui indices and HOMO/LUMO composition analysis. We have found that the top reducing agents are tryptophan, histidine, and tyrosine, and thestrongest binding can be expected from methionine and cysteine. Further study of the exact reactive sites in these high reactive amino acids provided the deep insight for the peptide design route for the targeted gold nanocluster formation.

Studies on the synthesis of amino acids XII.Solid-liquid phase transfer catalytic dicondensation of 1,4-diacety1-2,5-piperazinedione with aldehydes

3,6-Diarylidene-2,5-piperazinediones(2)and 3-alkylidene-6-arylidene-2,5-piperazfnediones (6)were synthesized from diacetyl-2,5-piperazinedione(1)under solid-liquid phase transfer catalytic conditions.2 could be easily convered to a-amino acid by reducing with zinc powder and hydrolyzing with concentrated hydrochloric acid.The effect of different phase transfer catalysts and reaction con- ditions were studied.