Notizen: Lysine as the Substrate Binding Site of Porphobilinogen Synthase of Rhodopseudomonas spheroides

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Abstract
The 14C labeled inactive protein obtained by sodium borohydride reduction of the enzyme, porphobilinogen synthase [EC 4.2.1.24] of R. sphaeroides, in the presence of [4-14C]5-aminolevulinic acid, gave on acid hydrolysis and subsequent electrophoresis or 2-dimensional chromatography a major radioactive spot which was confirmed to be N-.epsilon.-[4-(-5-aminovaleric acid)]lysine (ALA-lysine) by comparing its co-chromatographic and electrophoretic behavior with the chemically synthesized ALA-lysine. An .epsilon.-NH2 group of lysine residue of porphobilinogen synthase, is thus the binding site of the substrate, 5-aminolevulinic acid.