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Chemical modification of catalytic site of lipase from wheat germ: Altered structure-activity profile

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Title Chemical modification of catalytic site of lipase from wheat germ: Altered structure-activity profile
 
Creator Gopalakrishna, K N
Kumar, P Ramesh
Prakash, V
 
Description 28-34
Wheat germ lipase (WGL) was inactivated by
chemical modification of histidine, serine and carboxyl groups of Asp/Glu residues
with diethyl pyrocarbonate (DEPC), phenyl methyl sulfonyl fluoride (PMSF) and 1-ethyl-3-(3-dimethylaminopropyl)
carbodi -imide (EDC), respectively. Loss of activity of WGL was concentration dependent
of the inhibitor and at 30 mM PMSF
most of the activity of the enzyme was lost. The stoichiometry of modification
showed one mole of histidine, serine and two moles of carboxyl groups modified per
mole of protein. Kinetic measurements indicated that the inhibition of the enzyme
was competitive in nature. The modified enzyme was further characterized by far
UV-circular dichroic measurements of the secondary structure and fluorescence spectroscopy.
PMSF-modified enzyme showed decreased thermal stability, whereas no change was
observed in DEPC-modified enzyme as evidenced by differential scanning calorimetry.
These studies indicate that histidine, serine and Asp/Glu residues play an important
role in the catalytic function of WGL. The mechanism of loss of activity is due
to minor conformational change in the

microenvironment of the active site rather
than the gross conformational change of the molecule itself.
 
Date 2013-07-15T06:02:44Z
2013-07-15T06:02:44Z
2002-02
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/19744
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.39(1) [February 2002]