Enantioselective Enzymatic Cleavage of N‐Benzyloxycarbonyl Groups

Abstract

A new enzymatic process for the enantioselective cleavage of N-benzyloxycarbonyl (Cbz) groups from protected amino acids and related compounds has been developed. The Cbz-deprotecting enzyme was isolated from cell extracts of Sphingomonas paucimobilis SC 16113 and purified to homogeneity. The purified protein has a molecular weight of 155,000 daltons and a subunit size of 44,000 daltons.

Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group

“…No special specificity was observed for a single or a few Cbz-amino acid substrates as described by the Japanese or the German groups [2,3,6,14]. Moreover, Cbz-l-Proline is not a substrate for our enzyme, contrarily to the Sphingomonas paucimobilis SC16113 enzyme [5,11]. However our Cbz-deprotecting enzyme shares with all others previously described a strict enantioselectivity toward Cbz-l-amino acids.…”

“…In addition, such a deprotection is not enantioselective. Only a few examples of enzymatic hydrolytic deprotection of N-benzyloxycarbonyl derivatives, mainly N-␣-benzyloxycarbonyl aminoacids and oligopeptides have been reported, through the use of microbial whole cells [4], cell extracts [5] or purified urethane hydrolases [6][7][8][9][10][11][12][13][14], directed to various classes of ␣-aminoacids and reported to be highly enantioselective.…”

Enzyme Catalysis in the Synthesis of Active Pharmaceutical Ingredients

“…Hydrolytic removal of a CBz protecting group by an enzyme from Sphingomonas paucimobilis has been reported [25,26]. The initial study was on the removal of the CBz-group from CBz protected L-amino acid derivatives 63 (R = PhCH 2 , R 1 = alkyl, aryl, R 2 = COOH, X = O).…”

Biocatalytic Synthesis of Chiral Pharmaceutical Intermediates

“…An enantioselective enzymatic de-protection process has been developed that can be performed under mild conditions without damaging any otherwise susceptible groups in the molecule. A microbial culture was isolated from soil and identified as Sphingomonas paucimobilis strain SC 16113; this culture catalyzed the enantioselective cleavage of Cbz-groups from various Cbz-protected amino acids (97). Only Cbz--L-amino acids were de-protected, giving complete conversion to the corresponding L-amino acid.…”

“…The unreacted Cbz--D-amino acids were recovered in greater than 48 % yield and greater than 98 % e.e. (97). Cbz-cleaving enzyme has been purified and over-expressed in Escherichia coli (98).…”