Organ distribution, purification and characterization of kynureninase in Suncus murinus (Insectivora) and anthranilic acid level in the serum.
1. The highest kynureninase activity was measured in Suncus liver compared with other organs tested. The holo-enzyme activity detected in liver was 25%. 2. The enzyme mainly localized in liver cytosol was purified to a single protein band by heat treatment, ammonium sulfate fractionation, DEAE-sepharose, hydroxyapatite and phenyl-sepharose column chromatography. 3. The purified enzyme was effective for both kynurenine and 3-hydroxykynurenine, and showed the optimum pH at 8.5 against both substrates. 4. Km values were 250 microM, 18 microM and 70 microM for kynurenine, 3-hydroxykynurenine and pyridoxal 5'-phosphate, respectively. Various compounds such as histidine, aspartate and nicotinamide enhanced the enzyme activities. 5. Anthranilate, the product of kynureninase, was present at a concentration in Suncus serum of 1.96 microM. This value was higher than those of rat and human.
Ishikawa
T
T
Department of Biochemistry, Wakayama Medical College, Japan.
Okuno
E
E
Kawai
J
J
Kido
R
R
D000818:Animals; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D007526:Isoelectric Point; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D008970:Molecular Weight; D012788:Shrews / Q000378:metabolism*; D014018:Tissue Distribution; D062367:ortho-Aminobenzoates / Q000097:blood*
D062367:ortho-Aminobenzoates; C031385:anthranilic acid; D006867:Hydrolases; C021480:kynureninase