Biosynthesis—stereochemistry model

THE BIOSYNTHESIS-STEREOCHEMISTRY MODEL (CELMER S MODEL) OF THE ANSAMYCINS... 

Adenosine triphosphate, coupled reactions and. 1128-1129 function of, 157, 1127-1128 reaction with glucose, 1129 structure of, 157, 1044 S-Adenosylmethionine, from methionine, 669 function of, 382-383 stereochemistry of, 315 structure of, 1045 Adipic acid, structure of, 753 ADP, sec Adenosine diphosphate Adrenaline, biosynthesis of, 382-383 molecular model of, 323 slructure of, 24... 

Xie and Dixon [27] underlined that although some models of proanthocyanidin biosynthesis show the extension units arising from condensation of an leucoanthocyanidin-derived electrophile with the nucleophilic 8 or 6 position of the starter unit, this scheme fails because of stereochemistry of leucoanthocyanidin is most likely 2,3-trans, whereas, in many cases, the extension units are 2,3-cis. One possible solution for this stereochemical para-... 

Protein polymers based on Lys-25 were prepared by recombinant DNA (rDNA) technology and bacterial protein expression. The main advantage of this approach is the ability to directly produce high molecular weight polypeptides of exact amino acid sequence with high fidelity as required for this investigation. In contrast to conventional polymer synthesis, protein biosynthesis proceeds with near-absolute control of macromolecular architecture, i.e., size, composition, sequence, topology, and stereochemistry. Biosynthetic polyfa-amino acids) can be considered as model uniform polymers and may possess unique structures and, hence, materials properties, as a consequence of their sequence specificity [11]. Protein biosynthesis affords an opportunity to completely specify the primary structure of the polypeptide repeat and analyze the effect of sequence and structural uniformity on the properties of the protein network. 

Funayama et al. reported the possibility for the application of their model to the stereochemistry and biosynthesis of the Imown benzenoid ansamycin antibiotics [202]. According to the analysis, herbimycin A (86) seemed to possess the same biosynthetic building units as those of... 

About 70 naphthalenoid ansamycins have been reported until now. In most of these ansamycins, the ansa part is composed of 17 carbons, like the rifa-mycins, and in other instances the ansa moiety is composed of 23 carbons, like the naphthomycins [1]. Models for the biosynthesis and stereochemistry (Celmer s model), as applied to macrolide antibiotics [2], have been developed for these two types of ansamycins [3]. 

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