ABSTRACT
Indolyl-3-acetylaspartic acid (IAAsp) was detected in the urine of rats given indolyl-3-acetic acid (IAA) i.p. It was ascertained that the conversion of IAA into IAAsp could be carried out not only in plants but also in animals.
Subject(s)
Indoleacetic Acids/urine , Animals , Aspartic Acid/metabolism , Indoleacetic Acids/metabolism , Male , Rats , Tryptophan/metabolismABSTRACT
Plasma phenylalanine and tyrosine levels in rats which had been orally administered L-phenylalaninol and L-phenylalanine were determined. Since these amino acid levels in rats administered L-phenylalanine solution containing L-phenylalaninol were significantly lower than those in rats administered L-phenylalanine alone. L-phenylalaninol appears to inhibit the intestinal absorption of L-phenylalanine. This effect was more potent than that of cycloleucine. L-phenylalaninol inhibited the phenylalanine transport of everted sacs. The Km value of L-phenylalanine was 3.44 X 10(-3) M and the Ki value of L-phenylalaninol was 7.69 M 10(-3) M from Lineweaver-Burk plots. From these two curves, it appeared that L-phenylalaninol may competitively inhibit the intestinal transport of L-phenylalanine. The effects of L-phenylalanine, L-phenylalaninol and cycloleucine on the urinary excretions of Na+ and K+ in rats were also examined. Potassium excretion which increased on oral administration of L-phenylalanine, was suppressed by the administration of L-phenylalaninol but not administration of cycloleucine. L-phenylalaninol alone enhanced Na+ excretion in urine. These results confirmed that L-phenylalaninol shows inhibitory effects as potent as those of cycloleucine on the intestinal absorption of L-phenylalanine.
