title: Developmental changes in purine phosphoribosyltransferases in human and rat tissues.
abstract: 1. The hypoxanthine/guanine and adenine phosphoribosyltransferase activities in a wide variety of human tissues were studied during their growth and development from foetal life onward. A wide range of activities develop after birth, with especially high values in the central nervous system and testes. 2. Postnatal development of hypoxanthine/guanine phosphoribosyltransferase was also defined in the rat. Although there were increases in the central nervous system and testes, there was also a rise in activity in the liver, which was less marked in man. 3. A sensitive radiochemical assay method, using dTTP to inhibit 5'-nucleotidase activity, suitable for tissue extracts, was developed. 4. No definite evidence of the existence of tissue-specific isoenzymes of hypoxanthine/guanine or adenine phosphoribosyltransferase was found. Hypoxanthine/guanine phosphoribosyltransferase in testes, however, had a significantly different thermal-denaturation rate constant. 5. The findings are discussed in an attempt to relate activity of hypoxanthine/guanine phosphoribosyltransferase to biological function. Growth as well as some developmental changes appear to be related to increase in the activity of this enzyme.
mesh_terms: D000228:Adenine Phosphoribosyltransferase / Q000378:metabolism; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000254:growth & development; D004912:Erythrocytes / Q000201:enzymology; D006147:Guanine; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D007223:Infant; D007231:Infant, Newborn; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D010430:Pentosyltransferases / Q000378:metabolism*; D011489:Protein Denaturation; D051381:Rats; D013737:Testis / Q000201:enzymology* / Q000254:growth & development
chemical_list: D006147:Guanine; D010430:Pentosyltransferases; D000228:Adenine Phosphoribosyltransferase; D007041:Hypoxanthine Phosphoribosyltransferase