Characterization of the major form of cholecystokinin in human intestine: CCK-58.
Acid extracts of human intestines obtained from surgical samples or from organ donors contain cholecystokinin (CCK) immunoreactivity. From surgical samples, extracted and eluted quickly, greater than 75% of the CCK immunoreactivity eluted in the same region as purified canine CCK-58 during analytical reverse-phase high-pressure liquid chromatography (HPLC). A major portion of the CCK immunoreactivity from donor intestinal extracts also eluted in this region. This immunoreactivity has been purified from human intestinal extracts by a series of several reverse-phase and cation-exchange chromatographies. Amino acid and microsequence analysis showed that this immunoreactivity is human CCK-58. Tryptic digestion of purified human CCK-58 produced another immunoreactive form that eluted in the position of CCK-8 during analytical reverse-phase HPLC. The immunoreactivity of the trypsin-digested material was 2.6-fold higher than that of an identical sample of CCK-58 incubated without trypsin. Thus the carboxyl-terminal antibody used for radioimmunoassay cross-reacts greater than twofold less with human CCK-58. This diminished cross-reactivity would lead to an underestimation of the relative proportions of CCK-58 in tissue and plasma extracts. If CCK-58 is the major circulating form this diminished cross-reactivity would also lead to underestimations of the circulating levels of total CCK. Determination of human CCK-58 structure confirms that one of the major components of human CCK that expresses biological activity is CCK-58.
Eysselein
V E
VE
Harbor-University of California, Los Angeles, Department of Gastroenterology, Torrance 90502.
Eberlein
G A
GA
Schaeffer
M
M
Grandt
D
D
Goebell
H
H
Niebel
W
W
Rosenquist
G L
GL
Meyer
H E
HE
Reeve
J R
JR
D000595:Amino Acid Sequence; D002766:Cholecystokinin / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D007583:Jejunum / Q000032:analysis*; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000032:analysis; D010446:Peptide Fragments / Q000302:isolation & purification; D011863:Radioimmunoassay; D014357:Trypsin
D010446:Peptide Fragments; C038823:cholecystokinin 58; D002766:Cholecystokinin; D014357:Trypsin