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The present investigation shows the effect of alkaline pH on the structure-function relationship of lipase from wheat germ.There is a 70% decrease in lipase activity at pH 10.0, which decreases to 93% at pH 12.0 as compared to neutral pHactivity (Rajendran et al. 1990). This change is shown to be as a result of loss of a-helical structure with a concomitantincrease in a periodic structure. The results with fluorescence spectra and tyrosyl ionization indicate gradual exposure ofaromatic side chains of tyrosine and tryptophan to the bulk solvent along with the structural changes. The enzyme is in anextended form at alkaline pH with a volume change of -1300 ml/mol as also indicated by increase in reduced viscosity to12.5 ml/g and significant decrease in sedimentation coefficient. The kinetics of the reaction points to a cooper-activepseudo first-order reaction as determined by stopped-flow kinetic analysis in the ultra violet region. The inactivati6nmechanism appears to follow a two-step mechanism of a fast and a slow reaction.