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Purification and characterisation of two isozymes of pyruvate decarboxylase from Rhizopus oryzae

Paper ID Volume ID Publish Year Pages File Format Full-Text
18025 42710 2007 8 PDF Available
Title
Purification and characterisation of two isozymes of pyruvate decarboxylase from Rhizopus oryzae
Abstract

Pyruvate decarboxylases were purified and partially characterised for the first time from aerobically grown Rhizopus oryzae mycelium. Two very similar pyruvate decarboxylase isoenzymes were partially separated from each other by a purification protocol including ammonium sulphate precipitation, gel filtration chromatography and anion exchange chromatography. The subunit molecular weights of the enzymes were estimated to be 61 kDa for both. The pI values determined by two-dimensional electrophoretic analysis were 5.94 and 5.82 for the isoenzymes. The isoenzymes were similar in many kinetic aspects and the Km values were estimated as 3.9 and 4.5 mM for each of the enzymes. Both of the isozymes showed sigmoidal kinetics with a Hill coefficient of 1.8. Substrate inhibition was observed for both of the enzymes at pyruvate concentrations above 20 mM for one of the isoenzymes and 40 mM for the second isoenzyme. The enzymes were found in two different native forms; dimer and tetramer with estimated molecular weights of 120–128 and 272 kDa with the dimer being the predominant form. The optimum pH was between 6.3 and 6.5 for both.

Keywords
Rhizopus oryzae; Pyruvate decarboxylase; Purification; Characterisation
First Page Preview
Purification and characterisation of two isozymes of pyruvate decarboxylase from Rhizopus oryzae
Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 40, Issue 4, 5 March 2007, Pages 675–682
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering