ABSTRACT
Immunotitration of hypoxanthine-dehydrogenase confirms earlier findings according to which, in the liver, HXDH activity stays low throughout embryonic life and increases suddenly at the period of hatching.
Whether from liver, kidney, intestine, pancreas or mesonephros, HXDH appears to have the same electrophoretic mobility (in agar, agarose and starch gels), the same molecular weight (estimated to be about 290000 by Sephadex G 200 filtration) and the same immunochemical properties (as tested with 24 anti-liver, 18 anti-kidney, and 4 anti-mesonephros sera).
Various attempts to interfere with HXDH synthesis in vivo or in vitro (injection of substrate or liver extracts; explantation of fragments of mesonephros, metanephros or intestine from 9-to 12-day-old chick embryos on substrate-containing culture media; direct association of tissues containing high and low levels of enzyme) have so far failed.
