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Purification and characterization of dihydrofolate reductase from <i>Lactobacillus leichmannii</i>

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Title Purification and characterization of dihydrofolate reductase from Lactobacillus leichmannii
 
Creator Rao, K Narasimha
 
Description 121-129
Dihydrofolate reductase (DHFR) (5,6,7,8-THF:
NADDP+ oxidoreductase, EC 1.5.1.3) was purified 205-fold to apparent
homogeneity from the crude extracts of Lactobacillus leichmannii. It has
UV absorption maxima at 280 nm, Mr of 20,000, Stokes radius
of 0.34 nm and a S20,w value of 0.12 S. The preparation showed the presence
of 168 amino acid residues with threonine and lysine as the NH2- and
COOH- terminal end-groups respectively and a single reactive sulfhydryl group. pCMB
inhibited the enzyme activity (IC50 = 2μM). The enzyme has a pH
optimum of 7.4 and is thermally inactivated at >35°C. It is activated by 0.1
M KCl and KI and 2M urea. 3-4M urea completely inactivated
the enzyme. Enzyme has Km values of 3.5 μM and 6.2μ
M for NADPH and DHF respectively, and a Ki value of 7 nM
for MTX, the inhibition being competitive.
 
Date 2013-07-16T07:17:44Z
2013-07-16T07:17:44Z
2000-04
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/19819
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.37(2) [April 2000]