Hydrolytic cleavage of pyroglutamyl-peptide bond. I. The susceptibility of pyroglutamyl-peptide bond to dilute hydrochloric acid.
The susceptibility of the pyroglutamyl-peptide bond in some biologically active peptides, dog neuromedin U-8 fragment (pGlu-Phe-Leu-Phe-Arg-Pro-Arg-OH), human big gastrin fragment (pGlu-Leu-Gly-Pro-OH) and thyrotropin releasing hormone (TRH) fragments (pGlu-His-Pro-OH, pGlu-His-OH), to 1 N HCl under mild conditions and/or at 60 degrees C was studied. It was found that the N-terminal portion of pGlu-peptides is extremely labile to acid hydrolysis, giving not only the ring-opened product of the pyrrolidone moiety of the pGlu residue, but also the cleavage product of the pGlu-peptide linkage. The ring-opening reaction predominated over the cleavage reaction in hydrolysis of the four peptides in 1 N HCl at 60 degrees C. The ring-opening reaction and the cleavage reaction of pGlu-peptide linkage proceeded faster than the cleavage of internal peptide bonds. The rate of hydrolysis was affected by the reaction temperature, and the ring-operating reaction was greatly diminished at 4 degrees C in comparison with the cleavage reaction. Thus, the phenomenon that the pGlu-peptide bond is susceptible to dilute HCl as compared to the other peptide bond appears to be a general one.
Hashimoto
T
T
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Ohki
K
K
Sakura
N
N
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D005755:Gastrins / Q000737:chemistry; D006851:Hydrochloric Acid / Q000737:chemistry; D006868:Hydrolysis; D008969:Molecular Sequence Data; D015287:Neurokinin B / Q000031:analogs & derivatives / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013696:Temperature; D013973:Thyrotropin-Releasing Hormone / Q000737:chemistry
D005755:Gastrins; D010446:Peptide Fragments; D011498:Protein Precursors; C013706:big gastrin; D013973:Thyrotropin-Releasing Hormone; D015287:Neurokinin B; C038393:neuromedin B; D006851:Hydrochloric Acid; D011761:Pyrrolidonecarboxylic Acid