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Updated: Jul 11, 2026

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase
Published on: November 8, 2019
Purification and properties of 4-hydroxyphenylacetic acid 3-hydroxylase from Pseudomonas putida
S G Raju1, A V Kamath, C S Vaidyanathan
1Department of Biochemistry, Indian Institute of Science, Bangalore.
Abstract:
4-Hydroxyphenylacetic acid 3-hydroxylase is a key enzyme in the pathway for the microbial degradation of phenylalanine, tyrosine and many aromatic amines. This enzyme was purified to homogeneity from Pseudomonas putida by affinity chromatography. The protein had a molecular weight of 91,000 and was a dimer of identical subunits. It was a typical external flavoprotein monooxygenase and showed an absolute requirement of NADH for activity. The enzyme had a pH optimum of 7.5 and the Km values for 4-hydroxyphenylacetic acid and NADH were 2 x 10(-4) M and 5.9 x 10(-5) M respectively. It was strongly inhibited by heavy metal ions and thiol reagents, suggesting the possible involvement of -SH group(s) in enzyme reaction.
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