Sequence around the active center cystine of lipoamide dehydrogenase from pig heart, comparison with the E. coli enzyme.

Catalysis by lipoamide dehydrogenase involves the concerted action of the flavin and a cystine residue. Peptides containing this cystine residue have been previously isolated from E. coli and now from pig heart. The sequences of amino acid residues reveal a high degree of homology indicating a strict conservation of the region around the active site cystine during the long evolutionary period between these two species. The peptide sequences suggest a likely conformation of the polypeptide chain in the region of the flavin as well as the forces involved in substrate and flavin binding.