Journal of Protein Chemistry

, Volume 10, Issue 3, pp 291–299 | Cite as

Structural stability of lipase from wheat germ in alkalinepH1

  • K. Sudhindra Rao
  • S. Rajendran
  • A. N. Rajeshwara
  • V. Prakash
Article

Abstract

The present investigation shows the effect of alkalinepH on the structure-function relationship of lipase from wheat germ. There is a 70% decrease in lipase activity atpH 10.0, which decreases to 93% atpH 12.0 as compared to neutralpH activity (Rajendranet al. 1990). This change is shown to be as a result of loss ofa-helical structure with a concomitant increase in aperiodic structure. The results with fluorescence spectra and tyrosyl ionization indicate gradual exposure of aromatic side chains of tyrosine and tryptophan to the bulk solvent along with the structural changes. The enzyme is in an extended form at alkalinepH with a volume change of -1300 ml/mol as also indicated by increase in reduced viscosity to 12.5 ml/g and significant decrease in sedimentation coefficient. The kinetics of the reaction points to a cooperative pseudo first-order reaction as determined by stopped-flow kinetic analysis in the ultraviolet region. The inactivation mechanism appears to follow a two-step mechanism of a fast and a slow reaction.

Key words

Lipase wheat germ inactivation structure-function kinetics conformation 

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Copyright information

© Plenum Publishing Corporation 1991

Authors and Affiliations

  • K. Sudhindra Rao
    • 1
  • S. Rajendran
    • 1
  • A. N. Rajeshwara
    • 1
  • V. Prakash
    • 1
  1. 1.Biophysical Chemistry Unit, Food Chemistry DepartmentCentral Food Technological Research InstituteMysoreIndia

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