The parallel accumulation and distribution of two purine-oxidizing enzymes during frog development

• Main Author: Barrett, Dennis
• Format: Others
• Published: 1963
• Online Access: https://thesis.library.caltech.edu/6836/1/Barrett_d_1963.pdf; Barrett, Dennis (1963) The parallel accumulation and distribution of two purine-oxidizing enzymes during frog development. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0TRM-B219. https://resolver.caltech.edu/CaltechTHESIS:02272012-160448464 <https://resolver.caltech.edu/CaltechTHESIS:02272012-160448464>

<p>The patterns of two specialized and functionally related enzymes were investigated in the developing frog (Rana temporaria and Rana catesbeiana). Xanthine dehydrogenase (E.C. 1.2.1.) and uricase (E. C. 1. 7 . 3 . 2.) were found to remain apparently constant during the first ten days of normal development, both rising rapidly thereafter, beginning at the same larval stage. Comparison with enzymes of similar developmental pattern suggests this phase-specific increase is in preparation for the onset of digestive activity.</p> <p>The same parallelism between uricase and xanthine dehydrogenase was observed when determinations were extended to the organ level. Each enzyme was found in quantity in liver and kidney, and in trace amounts, all of about the same magnitude, in several other organs tested.</p> <p>By detecting radioactive tracer amounts of product, very low levels of xanthine dehydrogenase were measured in embryonic stages, probably corresponding to the order of small numbers of molecules per cell.</p> <p>Evidence was gathered to suggest that embryonic uricase accumulation is neither induced by its substrate nor involved with the subcellular particles in which the enzyme is found.</p>