Induction of angiotensin-converting enzyme inhibitory activity by acid-limited proteolysis of glyceraldehyde 3-phosphate dehydrogenase. 
Angiotensin-converting enzyme (ACE) inhibitors were excised from glyceraldehyde 3-phosphate dehydrogenase (GAPDH) preparations of tuna and porcine muscles by heating at 120 degrees C for 5 min in 1 M AcOH-20 mM HCl.  The inhibitors were then purified by successive chromatographies.  The final product from tuna was identified as Pro-Thr-His-Ile-Lys-Trp-Gly-Asp, which was the ACE inhibitor obtained from tuna muscle [Kohama et al. ( 1988) Biochem.  Biophys.  Res.  Commun.  155, 332-337].  The porcine ACE inhibitor was found to be Pro-Ala-Asn-Ile-Lys-Trp-Gly-Asp, which was identical to the porcine muscle GAPDH peptide 79-86.  These results strongly suggested that the ACE inhibitory octapeptides derived from GAPDH proteins by acid-limited proteolysis at Asp-Pro and Asp-Ala peptide bonds.