Intramolecular dehydratation of phenylthiocarbamyl aminoacids induced by α‐chymotrypsin

Synthesis of isomeric methyl- and dimethyl-substituted 4-benzylidene-2-phenyloxazolin-5-ones and ring-opened derivatives

“…Because the oxazolinones and the -benzamidomethyl cinnamates are potential substrates for proteolytic enzymes and because the acids would be the presumed hydrolysis product, these molecules were made and characterized. The structures of the oxazolinones (1) the esters (2), and the acids (3) are given in Scheme I. The molecules were readily synthesized in good yields by the general methods given in the Experimental Section.…”

Stereospecificity of α‐chymotrypsin. Changes of substrate configuration during enzymatic hydrolysis

“…With this molecule, which can be considered a cyclized form of methyl N&acetyl tryptophanate, an inversion of antipodal specificity has been observed, the D enantiomer being much more susceptible than the L one to o-chymotryptic hydrolysis [3].…”

“…The D isomer of MDCOMe is a specific substrate for a-chymotrypsin [3] and its hydrolysis yields the expected D-MDC. When L-MDCOMe is utilized as a substrate for cr-chymotrypsin a complete inversion of co& guration occurs since only the D-MDC can be found at the end point of the reaction.…”

“…The methyl esters (MDCOMe)* [3] were fixed by an overnight treatment of the acids with methanol:thionyl chloride 9: 1 and crystallized as hydrochlorides from methanol ethyl ether.…”

“…The hydrolysis of thiazolinones was followed at 365 nm ( fig. l), and of MDCOMe at 352 nm [3]. The *Abbreviations used: MDC = 1-methyl-3,4-dihydrop-carboline 3-carboxylic acid; MDCOMe = methyl-l-methyl-3,4-di hydra-p-carboline-3-carboxylate.…”