BCHM 316 Study Guide - Final Guide: Ketogenic Amino Acid, Porphobilinogen, Porphyrin
13 Jul 2018
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Glycine = major precursor in biosynthesis of porphyrins. There are two pathways into making -aminolevulinate which is derived from glycine in higher eukaryotes. Different pathways depending on whether it is an eukaryote, or plant/bacteria/algae. Higher eukaryotes: glycine reacts with succinyl-coa , yielding -amino- - ketoadipate. In plants, algae,most bacteria: glutamate is esterified to glutamyl-trna^glu, reduced by nadph (converts glutamate to glutamate-1-semialdehyde) G-1-s is cleaved from trna -- then, an aminotransferase converts g-1-s to. Porphobilinogen: monopyrrole derivative made from two molecules of - Porphyrins (protoporphyrin) are made from four molecules of porphobilinogen. Porphyrin biosynthesis is regulated in higher eukaryotes by heme, which serves as a feedback inhibitor of early steps in the synthetic pathway. Genetic defects in the biosynthesis of porphyrins can lead to the accumulation of pathway intermediates, causing a variety of human diseases known collectively as porphyrias ! Only a few species can convert atmospheric nitrogen into forms useful for living organisms.
