Definitions for uroporphyrinogens
This page provides all possible meanings and translations of the word uroporphyrinogens
U.S. National Library of Medicine
Porphyrinogens which are intermediates in heme biosynthesis. They have four acetic acid and four propionic acid side chains attached to the pyrrole rings. Uroporphyrinogen I and III are formed from polypyrryl methane in the presence of uroporphyrinogen III cosynthetase and uroporphyrin I synthetase, respectively. They can yield uroporphyrins by autooxidation or coproporphyrinogens by decarboxylation.
Uroporphyrinogens are cyclic tetrapyrroles with four propionic acid groups and four acetic acid groups. There are four forms, which vary based upon the arrangements of the "P" and "A" groups: In the "I" variety, the order repeats four times: AP-AP-AP-AP. In the "III" variety, the fourth is reversed: AP-AP-AP-PA. This is the most common form. In the synthesis of porphyrin, it is created from the linear tetrapyrrole hydroxymethylbilane by the enzyme uroporphyrinogen III synthase, and is further converted into coproporphyrinogen III by the enzyme uroporphyrinogen III decarboxylase . The "II" and "IV" varieties can be created synthetically, but do not appear in nature.
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"uroporphyrinogens." Definitions.net. STANDS4 LLC, 2014. Web. 28 Jul 2014. <http://www.definitions.net/definition/uroporphyrinogens>.