Molecular Recognition for the Enantioselective Hydrolysis of Amino Acid Esters in Functional Molecular Assembly Systems

Abstract

Enantioselective hydrolysis of amino acid esters by L-histidine derivatives in the molecular assemblies composed of single- and double-chain surfactants was investigated.
The remarkably high enantioselectivity (k^L_{a, obsd}/ k^D_{a, obsd}=1000) was attained for the hydrolysis of longchained substrates (N-dodecanoyl-D (L)-phenylalanine p-nitrophenyl ester; C₁₂-D( L ) - Phe-PNP) catalyzed by the active tripeptide (N- (benzyloxycarbony1)-L-phenylalanyl-L-histidyl-L-leucine; Z-PheHisLeu) in the coaggregate systems composed of 41 mol% hexadecyltrimethylammonium bromide (CTAB) and 59 mol% ditetradecyldimethylammonium bromide (2C₁₄Br) at the specific ionic strength (μ=0.02).
Furthermore, the computer modeling (MOPAC calculation)study suggests that a favorable molecular recognition between the substrate and the catalyst through the effective hydrophobic interactions and hydrogen bonds should be very important for the enhancement of enantioselectivity.