Purification and characterization of enkephalin-related peptides released by in vitro peptic digestion of bovine plasma proteins.
In vitro pepsin treatment of plasma proteins generates biologically active peptides such as enkephalin-related peptides. These peptides were characterized using chromatographic techniques along with a radioimmunoassay procedure involving the use of Leu-enkephalin and Met-enkephalin antisera. Serum albumin is the only existing source of Met-enkephalin-immunoreactive peptides. One of these peptides consists of nine residues with the sequence NH2-Glu-Lys-Leu-Gly-Glu-Tyr-Gly-Phe-Gln; a second immunoreactive peptide might be the hexapeptide NH2-Gly-Glu-Tyr-Gly-Phe-Gln, which has been already identified in a rat serum albumin hydrolysate. Our results indicate that immunoglobulins constitute the main source of Leu-enkephalin-immunoreactive peptides. Immunoreactive NH2-Tyr-Phe-Leu was isolated from pepsin-treated bovine immunoglobulins. Binding experiments and cyclic nucleotide measurements suggested that this peptide was an enkephalin-related peptide. Similar experiments could be carried out to identify the proteins that contain enkephalin-like peptide sequences with the view to investigating the various biological processes occurring in enzymatically treated proteins.
Laboratoire de Biochimie, Faculté des Sciences, Limoges, France.
I
I
Garreau
C
C
Pejoan
P
P
Bressollier
B
B
Verneuil
K
K
Cucumel
A
A
Cupo
D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism; D004745:Enkephalins / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D010434:Pepsin A; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism
D001798:Blood Proteins; D004745:Enkephalins; D009842:Oligopeptides; D011957:Receptors, Opioid; D000242:Cyclic AMP; D010434:Pepsin A