De Caro A, Multigner L, Lafont H, Lombardo D, Sarles H
Biochem J. 1984 Sep 15;222(3):669-77. doi: 10.1042/bj2220669.
A CaCO3-crystal-growth inhibitor was isolated from human pancreatic stones by using EDTA demineralization, followed by DEAE-Trisacryl chromatography. The isolated inhibitor was found to be a phosphoglycoprotein with Mr 14017 and having an unusual chemical composition. It is characterized by a high (42%) acidic amino acid content, but lacks methionine and gamma-carboxyglutamic acid. The protein contains 2.65 mol of P/mol of protein, as phosphoserine (2 mol) and phosphothreonine (0.5 mol). Isoelectric focusing of the protein yields one major band corresponding to an isoelectric point of 4.2. Immunochemical quantification of the crystal-growth inhibitor in pure pancreatic juice reveals that it constitutes 14% of the normal exocrine secretion. Our findings demonstrate that this is a novel secretory protein, which has no enzymic activity and which maintains pancreatic juice in a supersaturated state with respect to CaCO3.
通过使用乙二胺四乙酸（EDTA）脱矿质法，随后进行二乙氨基乙基-三丙烯酸树脂（DEAE-Trisacryl）色谱法，从人胰石中分离出一种碳酸钙晶体生长抑制剂。所分离出的抑制剂是一种分子量为14017的磷酸糖蛋白，其化学组成不同寻常。其特点是酸性氨基酸含量高（42%），但缺乏甲硫氨酸和γ-羧基谷氨酸。该蛋白质含有2.65摩尔磷/摩尔蛋白质，以磷酸丝氨酸（2摩尔）和磷酸苏氨酸（0.5摩尔）的形式存在。该蛋白质的等电聚焦产生一条主要条带，对应于4.2的等电点。对纯胰液中晶体生长抑制剂的免疫化学定量分析表明，它占正常外分泌液的14%。我们的研究结果表明，这是一种新型分泌蛋白，它没有酶活性，并且能使胰液相对于碳酸钙保持过饱和状态。
