Digestion of purine ribonucleotides by intestinal enzymes of the developing rat fetus

¹ Department of Biochemistry, University of Pennsylvania Medical School, Philadelphia, Pennsylvania

Small segments of intestine from fetal rats were incubated in the presence of guanosine monophosphate (GMP) or adenosine monophosphate (AMP) and the products of hydrolysis identified by paper chromatography. All of the enzymes required to decompose GMP and AMP to uric acid and allantoin that were found in the adult intestine were also found in the 19-day fetal intestine. These were: nucleotide phosphatase, adenosine deaminase, guanosine-inosine phosphorylase, guanase, xanthine oxidase, and presumably uricase. The 16-day fetal intestine lacked xanthine oxidase, at least in sufficient amount to give ultraviolet spots on the chromatograms, for xanthine and uric acid. In one experiment on a 15-day fetus, inosine phosphorylase was also lacking, and one on a 13-day fetus gave positive evidence of only nucleotide phosphatase. It is inferred that there is a gradual development of these enzymes in the fetal life of the rat, the ones decomposing the more complex molecules of the nucleotides and the nucleosides appearing earlier than those decomposing the bases. There are, however, no data from these experiments to indicate how early uricase is formed, since uric acid was not found among the decomposition products of GMP or AMP digestion until the 19th day.

Key Words: development of intestinal enzymes

Submitted on March 3, 1965