PMID: 24171Dec 29, 1977

Kinetic studies on 3-hydroxykynureninase from rat liver

Molecular and Cellular Biochemistry
K HaglundJ Ford


3-Hydroxykynureninase was purified from rat liver. The Michaelis constants for L-kynurenine and L-3-hydroxykynurenine were determined to be 2.33 X 10(-4)M and 6.85 X 10(-5)M, respectively, at pH 8.41 and 37 degrees. With L-kynurenine as substrate, the enzyme was competitively inhibited by L-alanine, 3-hydroxyanthranilic acid, and several other compounds which contained structural features of either amino acid or aryl portions of the substrate. The effect of pH on the initial velocity, maximal velocity, and Michaelis constant, using L-kynurenine as substrate, was studied. Maximal velocity was strongly pH-dependent, with a maximum at pH 8.4. The Michaelis constant decreased from 11.4 X 10(-4)M at pH 7.1 to 1.30 X 10(-4)M at pH 9.0. Logarithmic plots of these data showed pKa's for functional groups ionizing in the enzyme-substrate complex and free enzyme active center of 7.6 and 8.5, respectively. Possible groups responsible for these ionizations were discussed.


Jan 1, 1989·Comparative Biochemistry and Physiology. B, Comparative Biochemistry·T IshikawaR Kido
Aug 1, 1987·Human Genetics·M BlandfortF Vogel


Nov 1, 1976·FEBS Letters·K TanizawaK Soda
Apr 2, 1973·Biochemical and Biophysical Research Communications·C E McDermottF H Gaertner
Jul 31, 1973·Biochemistry·M MoriguchiK Soda
May 1, 1970·American Journal of Physical Anthropology·D F RobertsJ O Willson
Feb 19, 1971·Biochemical and Biophysical Research Communications·J R Turner, H Drucker
Aug 1, 1953·The Biochemical Journal·M DIXON
Jun 17, 1961·Annals of the New York Academy of Sciences·R G BATES

Related Concepts

Amino Acid [EPC]
Hydrogen-Ion Concentration
Rat Liver
In Vitro [Publication Type]
3-Hydroxyanthranilic Acid

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