A radioimmunoassay for the tripeptide Gly-Trp-Met, a major metabolite of endogenous cholecystokinin in brain.
We developed a specific and sensitive radioimmunoassay for the tripeptide Gly-Trp-Met (GWM) after its derivatization with p-benzoquinone. Measurable amounts of endogenous GWM-like immunoreactivity (GWM-ir), coeluting in HPLC with authentic GMW were detected in the medium of depolarized slices of rat cerebral cortex. The tripeptide GWM appears as the major inactive CCK-8 metabolite since a major fraction of CCK-8-ir released from the slices was apparently recovered in the medium as GWM. In addition, in the presence of the serine reagent diisopropylfluorophosphate, a strong decrease of GWM formation was observed to accompany the corresponding increase of CCK-8-ir recovery in medium. The present study confirms that (a) serine peptidase(s) is(are) responsible for inactivating endogenous CCK-8 in brain as previously proposed (Rose et al. Proc Natl Acad Sci USA 1988; 85:8326).
Rose
C
C
Unité de Neurobiologie et Pharmacologie de I'INSERM, Centre Paul Broca, Paris, France.
Vargas
F
F
Bourgeat
P
P
Schwartz
J C
JC
D000595:Amino Acid Sequence; D000818:Animals; D016227:Benzoquinones / Q000737:chemistry; D002540:Cerebral Cortex / Q000737:chemistry* / Q000276:immunology; D002766:Cholecystokinin / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry; D007531:Isoflurophate / Q000737:chemistry; D009842:Oligopeptides / Q000032:analysis* / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013439:Sulfhydryl Reagents / Q000737:chemistry
D016227:Benzoquinones; D007202:Indicators and Reagents; D009842:Oligopeptides; D013439:Sulfhydryl Reagents; C102204:glycyl-tryptophyl-methionine; D007531:Isoflurophate; C004532:quinone; D002766:Cholecystokinin