Erniedrigte d-Aminosäureoxydase-Wirksamkeit im Organismus tumorkranker Ratten

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Abstract
White adult rats of both sexes were inoculated under the skin with fresh minced Walker tumor tissue. The tumors grew rapidly and weighed 5-40 g. within 2-4 wks. Litter mates served as control subjects. The rats were killed by decapitation, the livers or kidneys were ground with sand at 0[degree] and the mixture extracted with M/5 phosphate buffer, pH 8.0. The amino acid oxidase activity of the extract was estimated in the Warburg apparatus by determining the O2 uptake in the presence of d( + )-phenylalanine for a period of 3 hrs. The d-amino acid oxidase consists of a specific protein and a dissociably bound prosthetic group, the alloxazin adenine dinucleotide. One molecule of d(+ )-phenylalanine took up 1-1.7 atoms of O, forming phenylpyruvic acid and phenylacetic acid, and liberating 1 molecule of NH3. The amino acid oxidase activity of extracts from the tissues of rats with Walker carcinoma was considerably less than the activity of extracts from the tissues of the control or normal rats. There was no significant difference in the oxidase activity of tissues from [male] and [female] rats, and between the wts. of the livers and kidneys of the normal and tumor-bearing rats. There was no difference in the oxidase activity of normal and tumor-bearing rats towards 1( [long dash] )-phenylalanine.