Hydrolysis of <img src='http://www.niscair.res.in/jinfo/smaller.gif' border=0>,<img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-tryptophan isopropyl Ester catalysed by β-cyclodextrin

Abstract

β-Cyclodextrin (BCD) catalysed hydrolysis D,L-tryptophan isopropyl ester is found to be <i>p</i>H dependent. The <i>p</i>H rate constant profiles show that the <i>k</i>_obsvalues for the BCD catalysed reactions are higher than those of the control in the <i>p</i>Hrange 9.8 to 12.9. The reaction follows Michaelis-Menten type kinetics exhibiting substrate saturation. Michaelis-Menten treatment results in determination of <i>K</i>_D(0.067 <i>M) </i> and <i>k</i>_cat(0.015<i> M^-</i>¹ min ^-1). A <i>k</i>_cat/k_un values of 0.94 has been determined. Tryptophan, the hydrolysis product formed exhibited enantiometric excess of 7.9 to 18.4% of the (-) antipode n reactions catalysed by BCD, heptakis-2,6-di-O-methyl-β-cyclodextrin (DM-BCD), BCD-epichlorohydrin poIymer (BCD-polymer) and a 1:1 complex of Cu(II)-β- cyclodextrin (Cu(Il)-BCD).