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B6db references: 86192490

type Journal Article
authors Der Garabedian, P. A.; Lotti, A. M.; Vermeersch, J. J.
title 4-Aminobutyrate:2-oxoglutarate aminotransferase from Candida. Purification and properties
journal Eur J Biochem
ui 86192490
year (1986)
volume 156
number 3
pages 589-96.
keywords 4-Aminobutyrate Transaminase/antagonists & inhibitors/*isolation & purification/metabolism
abstract An enzyme which catalyzes the transamination of 4-aminobutyrate with 2- oxoglutarate was purified 588-fold to homogeneity from Candida guilliermondii var. membranaefaciens, grown with 4-aminobutyrate as sole source of nitrogen. An apparent relative molecular mass of 107,000 was estimated by gel filtration. The enzyme was found to be a dimer made up of two subunits identical in molecular mass (Mr 55,000). The enzyme has a maximum activity in the pH range 7.8-8.0 and a temperature optimum of 45 degrees C. 2-Oxoglutarate protects the enzyme from heat inactivation better than pyridoxal 5'-phosphate. The absorption spectrum of the enzyme exhibits two maxima at 412 nm and 330 nm. The purified enzyme catalyzes the transamination of omega-amino acids; 4- aminobutyrate is the best amino donor and low activity is observed with beta-alanine. The Michaelis constants are 1.5 mM for 2-oxoglutarate and 2.3 mM for 4-aminobutyrate. Several amino acids, such as alpha,beta- alanine and 2-aminobutyrate, are inhibitors (Ki = 38.7 mM, Ki = 35.5 mM and Ki = 33.2 mM respectively). Propionic and butyric acids are also inhibitors (Ki = 3 mM and Ki = 2 mM).
last changed 2002/11/04 17:41

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