| Abstract: | Glutamate dehydrogenase GDH] from the mucosa of sheep rumen was partly purified and characterized. In chromatography on DEAE cellulose, GDH activity separated into two fractions. Fraction I, isolated at a low NaCl gradient concentration, was not affected by Zn2+ or by the purine nucleotides GTP and AMP. The chromatographic behaviour of fraction II was the same as the parallel fraction isolated from the liver by the same technique. The activity of fraction II and the liver fraction was strongly inhibited by Zn2+ in 10(-6) to 3.10(-5) mol/1 concentration and by GTP in 10(-5) to 2.10(-5) mol/1 concentration. It was activated by AMP in 5.10(-6) to 6.10(-5) mol/1 concentration and by leucine in 3.10(-3) to 10(-2) mol/1 concentration. The coenzyme specificity of fraction I was greater for NADPH than for NADH. In the case of fraction II, like the fraction isolated from sleep liver, it was greater for NADH than for NADPH. It is concluded from the different effect of Zn2+ and of purine nucleotides on the enzyme activity of the fractions isolated from rumen mucosa that the mucosa of the sheep rumen contains two enzymes with GDH activity, one of which probably adsorbed] is of bacterial origin and the other is a constitutive tissue enzyme of the rumen wall. |
