Ascorbic acid and protein metabolism.

Abstract

1. Guinea pig maintained on a vitamin C and tryptophan deficient diet dies of scurvy earlier (12-15 days).2. In an insufficient vitamin C feeding, the appearance of scurvy can be delayed by administrating anthranilic acid.3. Experimentally induced alcaptonuria disappears by giving anthranilic acid. The effects of glutathione and Na2S2O3 are not apparent. Vitamin C and anthranilic acid have no effect on congenital alcaptonuria.4. The oxidation by liver homogenate of p-hydroxyphenylpyruvate and homogentisic acid is accelerated by 5-hydroxyanthranilic acid, which has no effect on the oxidation of 2, 5-dihydroxyphenylpyruvate. Consequently, the efficacy of anthranilic acid is ascribable to the action of 5-hydroxyanthranilic acid.5. Indolelactic acid appears in the urine of the guinea-pig fed a vitamin C deficient diet when tryptophan is administered to the animal.6. A high casein (40%) diet causes an earlier induction of scurvy.7. The content of vitamin C in the guinea-pig liver rapidly decreases by the administration of tyrosine, cystine and histidine, but is little influenced by alanine, glutamic acid and arginine.8. The length of survival of the guinea-pig on an insufficient vitamin C diet is prolonged by more than one week by the addition of homogentisic acid.9. 5-Hydroxyanthranilic and homogentisic acid are therefore capable of sparing vitamin C.10. A new modification for the estimation of benzoquinoneacetic acid was proposed.11. When butyric acid and tyrosine are simultaneously injected to the guinea pig maintained on a vitamin C deficient diet, benzoquinoneacetic acid is excreted in the urine and cataract appears in the eye lens.12. By using the 2, 6-dichlorophenolindophenol, 2, 4-dinitrophenylhydrazine, and ascorbic oxidase methods, it was proved that 2, 3-diketogulonic acid is converted to ascorbic acid by the rat and rabbit liver, but not by the liver slice and homogenate of the guinea pig tissues.13. Diketogulonic acid was estimated in tissues and organs of the rat, rabbit, guinea pig and hatching eggs.14. It was established by the use of the rabbit lens extract that diketogulonic acid increases following the formation of ascorbic acid from mannose, whereas in the traumatic cataractal lens the diketogulonic acid but not ascorbic acid is formed from mannose indicating that in the normal lens ascorbic acid is produced through diketogulonic acid, contrary to the cataraetal lens.15. It was discussed that the metabolisms of ascorbic acid and protein (amino acids) interact on each other and that diketogulonic acid is an intermediate metabolite of ascorbic acid.