de Bruijn M A, Mok K S, Nibbering C P, Out T, Van Marle J, Stellaard F, Tytgat G N, Groen A K
Department of Gastrointestinal and Liver Disease, Academic Medical Center, Amsterdam, The Netherlands.
Gastroenterology. 1996 Jun;110(6):1936-44. doi: 10.1053/gast.1996.v110.pm8964421.
BACKGROUND & AIMS: Biliary concanavalin A-binding glycoprotein (CABG) contains cholesterol crystallization-promoting activity that is not accounted for by the pronucleators that have been characterized in this fraction. The aim of this study was to isolate and characterize the missing activity.
Biliary glycoprotein was isolated using concanavalin A-Sepharose. Promoting activity in CABG was purified using density gradient ultracentrifugation.
Activity in CABG separated into two fractions at low (1.08) and high (1.29) density, which showed different crystallization kinetics in a model bile. The high-density fraction had a late onset time (49.2 +/- 17.8 hours) but a high crystal growth rate (13.4 +/- 5.2 micrograms. mL-1.h-1). The low-density fraction had a rapid onset time (33.9 +/- 20.9 hours) but a slower growth rate (6.5 +/- 3.8 micrograms.mL-1 .h-1). The high-density fraction was not further characterized in this study. The low-density fraction contained solid particles consisting of lipid and very little protein, and the activity was fully pronase resistant. Delipidation of the low-density fraction removed all activity.
A potent pronase-resistant nucleation-promoting activity was activated from human bile and characterized. The low-density fraction may be responsible for the rapid nucleation in bile from typical patients with fast-nucleating gallstones.
胆汁伴刀豆球蛋白A结合糖蛋白（CABG）具有促进胆固醇结晶的活性，而该组分中已鉴定的促核剂无法解释这种活性。本研究的目的是分离并鉴定这种缺失的活性。
使用伴刀豆球蛋白A - 琼脂糖分离胆汁糖蛋白。通过密度梯度超速离心纯化CABG中的促进活性。
CABG中的活性在低密度（1.08）和高密度（1.29）下分离成两个组分，在模拟胆汁中表现出不同的结晶动力学。高密度组分起始时间较晚（49.2±17.8小时），但晶体生长速率较高（13.4±5.2微克·毫升⁻¹·小时⁻¹）。低密度组分起始时间较快（33.9±20.9小时），但生长速率较慢（6.5±3.8微克·毫升⁻¹·小时⁻¹）。本研究未对高密度组分进行进一步鉴定。低密度组分包含由脂质和极少蛋白质组成的固体颗粒，且该活性完全抗胰蛋白酶。低密度组分去脂后消除了所有活性。
从人胆汁中激活并鉴定了一种有效的抗胰蛋白酶促核活性。低密度组分可能是快速形成结石的典型患者胆汁中快速成核的原因。
