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M9610021.TXT
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1996-01-30
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Document 0021
DOCN M9610021
TI Purification and characterization of malate dehydrogenase from
Cryptococcus neoformans.
DT 9601
AU Mahmoud YA; el Souod SM; Niehaus WG; Department of Biochemistry and
Anaerobic Microbiology, Virginia; Polytechnic Institute and State
University, Blacksburg 24061,; USA.
SO Arch Biochem Biophys. 1995 Sep 10;322(1):69-75. Unique Identifier :
AIDSLINE MED/96004781
AB The NAD-dependent malate dehydrogenase (EC 1.1.1.37) was purified from
Cryptococcus neoformans, a basidiomycetious yeast that is an
opportunistic pathogen of AIDS patients. The purified enzyme was a dimer
of 35 kDa subunits that exhibited uncompetitive substrate inhibition by
oxalacetate, typical for mitochondrial malate dehydrogenases from other
sources. Product inhibition studies indicated an ordered sequential
kinetic mechanism, with pyridine dinucleotide being the substrate that
binds to the free enzyme form. Unique aspects of this malate
dehydrogenase were inhibition by zinc ion, competitive versus malate
with Ki of 30 microM, and inhibition by heparin. Heparin inhibition was
competitive versus either NAD or malate, with Ki of 0.35 microM. Heparin
molecules of nominal molecular weight of 30,000 or 3000 were equally
effective inhibitors. A model is presented to explain the high affinity
of the enzyme for heparin.
DE AIDS-Related Opportunistic Infections/DRUG THERAPY/MICROBIOLOGY Binding
Sites Cryptococcosis/COMPLICATIONS/DRUG THERAPY/MICROBIOLOGY
Cryptococcus neoformans/*ENZYMOLOGY/PATHOGENICITY Drug Resistance,
Microbial Heparin/METABOLISM/PHARMACOLOGY Human Hydrogen-Ion
Concentration Kinetics Malate Dehydrogenase/ANTAGONISTS &
INHIB/CHEMISTRY/*ISOLATION & PURIF Molecular Weight NAD/PHARMACOLOGY
Oxaloacetates/PHARMACOLOGY Protein Conformation Support, Non-U.S.
Gov't Support, U.S. Gov't, P.H.S. JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).