The parallel accumulation and distribution of two purine-oxidizing enzymes during frog development
<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...
| Summary: | <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>
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