The molecular nature of cholecystokinin in plasma. An in vivo immunosorption study in rabbits.
The nature of cholecystokinin (CCK) in rabbit plasma was examined by means of a novel in vivo immunosorption procedure. Cholecystokinin (CCK) antibodies in 11 rabbit antisera were denatured, and the released peptides characterized by size and reversed-phase chromatography. Five of six antisera specific for the COOH terminus of CCK contained substantial amounts of CCK-22- and CCK-8-like peptides and small amounts of CCK-33-like peptides (range, 120 to 1140 nmol/l antiserum). In contrast, neither antisera for the NH2-terminus and mid-sequence of porcine CCK-33 nor antisera against the glycine-extended COOH terminus released CCK peptides. Postprandial acidified plasma from non-immunized rabbits concentrated in vitro also contained mainly CCK-22- and -8-like peptides, whereas extracts of rabbit duodenum and jejunum in addition contained forms resembling CCK-58, -39, and/or -33. The results show that mainly small molecular forms of CCK circulate in rabbits, and that NH2-terminal and mid-sequences of porcine and human CCK-33 differ from those of rabbit CCK-33. The results support the contention that plasma in most mammals contains small molecular forms of CCK.
Rehfeld
J F
JF
Dept. of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark.
D000595:Amino Acid Sequence; D000818:Animals; D002766:Cholecystokinin / Q000097:blood* / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004386:Duodenum / Q000737:chemistry; D005755:Gastrins / Q000032:analysis; D007163:Immunosorbent Techniques; D007583:Jejunum / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments; D011498:Protein Precursors / Q000032:analysis / Q000378:metabolism; D011817:Rabbits; D011863:Radioimmunoassay
D005755:Gastrins; D010446:Peptide Fragments; D011498:Protein Precursors; C013706:big gastrin; C060249:procholecystokinin; D002766:Cholecystokinin