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B6db references: 78109411

type Journal Article
authors Kito, K.; Sanada, Y.; Katunuma, N.
title Mode of inhibition of ornithine aminotransferase by L-canaline
journal J Biochem (Tokyo)
ui 78109411
year (1978)
volume 83
number 1
pages 201-6.
keywords Amino Acids/pharmacology
abstract The mechanism of inhibition of ornithine aminotransferase [EC] by L-canaline (alpha-amino-gamma-amino-oxybutyric acid) was investigated. Spectral changes of pyridoxal 5'-phosphate in ornithine aminotransferase on addition of L-canaline showed that L-canaline formed an oxime-type compound with pyridoxal 5'-phosphate that had the same spectra as the compound formed on addition of hydroxylamine to the holoenzyme. Kinetic studies indicated that hydroxylamine was a reversible noncompetitive inhibitor, whereas L-canaline was an irreversible inhibitor of ornithine aminotransferase. Other analogs, such as delta-aminovaleric acid and alpha-N-acetyl-L-ornithine, also reacted with the pyridoxal 5'-phosphate of the enzyme, but these compounds were competitive inhibitors with respect to L-ornithine. L- Canaline and hydroxylamine also reacted with pyridoxal 5'-phosphate in pig heart aspartate aminotransferase [EC] to produce an oxime, but both of them were reversible and noncompetitive inhibitors of the enzyme. The Ki value of hydroxylamine for ornithine aminotransferase was 4.3 X 10(-7) M and those of L-canaline and hydroxylamine for aspartate aminotransferase were 1.7 X 10(-4) M and 2.2 X 10(-5) M, respectively.
last changed 2002/11/04 17:41

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