Paloheimo L I, Rehfeld J F
Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Denmark.
Clin Chim Acta. 1995 Jun 30;238(1):21-33. doi: 10.1016/0009-8981(95)06055-i.
A procedure for processing-independent quantitation of procholecystokinin (proCCK) and its products has been applied to plasma. The procedure is based on tryptic cleavage after Lys61 and Arg71 with subsequent monospecific radioimmuno-analysis of fragment 62-71 of human proCCK, which again corresponds to fragment 1-10 of CCK-22. The detection limit of the analysis was 0.2 pmol/l. Plasma was extracted with ethanol. In plasma from 13 healthy volunteers the basal concentration with the above-mentioned radioimmunoassay was 1.1 +/- 0.1 pmol/l (mean +/- S.E.M.) before, and 13.7 +/- 0.6 pmol/l after, incubation with trypsin. Two hours after ingestion of a mixed meal, the plasma concentration was 2.0 +/- 0.1 pmol/l before, and 21.7 +/- 1.2 pmol/l after tryptic cleavage. With a conventional CCK radioimmunoassay specific for the C-terminally amidated and O-sulfated bioactive epitope, the concentration was 1.0 +/- 0.1 pmol/l in the basal state and 4.2 +/- 0.4 pmol/l 2 h after a meal. Tryptic cleavage did not increase the concentrations of amidated, bioactive CCK peptides. In plasma from 37 patients with the carcinoid syndrome, the basal concentration of proCCK and its products was 14.1 (2.8-150.4) pmol/l (median (range)), compared with 0.3 (0-18.8) pmol/l for carboxyamidated CCK. Only two patients had significantly elevated CCK concentrations. We conclude that processing-independent analysis is useful for quantitation of proCCK and its products in plasma, since it quantitates CCK cell secretion more accurately than conventional CCK assays.
一种用于对前胆囊收缩素（proCCK）及其产物进行与加工过程无关的定量分析方法已应用于血浆。该方法基于在赖氨酸61和精氨酸71之后进行胰蛋白酶切割，随后对人proCCK的62 - 71片段进行单特异性放射免疫分析，该片段又对应于CCK - 22的1 - 10片段。该分析的检测限为0.2 pmol/l。血浆用乙醇提取。在13名健康志愿者的血浆中，用上述放射免疫测定法测得的基础浓度在胰蛋白酶孵育前为1.1±0.1 pmol/l（平均值±标准误），孵育后为13.7±0.6 pmol/l。摄入混合餐后两小时，血浆浓度在胰蛋白酶切割前为2.0±0.1 pmol/l，切割后为21.7±1.2 pmol/l。使用针对C末端酰胺化和O - 硫酸化生物活性表位的传统CCK放射免疫测定法，基础状态下浓度为1.0±0.1 pmol/l，餐后2小时为4.2±0.4 pmol/l。胰蛋白酶切割并未增加酰胺化生物活性CCK肽的浓度。在37名类癌综合征患者的血浆中，proCCK及其产物的基础浓度为14.1（2.8 - 150.4）pmol/l（中位数（范围）），而羧酰胺化CCK的浓度为0.3（0 - 18.8）pmol/l。只有两名患者的CCK浓度显著升高。我们得出结论，与加工过程无关性分析对于血浆中proCCK及其产物的定量分析是有用的，因为它比传统的CCK测定法更准确地定量CCK细胞分泌。
