关于来自牛巩膜的硫酸皮肤素蛋白聚糖，在氯化铯和硫酸铯中进行等密度离心研究。

Isopycnic-centrifugation studies in caesium chloride and in caesium sulphate on dermatan sulphate proteoglycans from bovine sclera.

作者信息

Sheehan J K, Carlstedt I, Cöster L, Malmström A, Fransson L A

出版信息

Biochem J. 1981 Dec 1;199(3):581-9. doi: 10.1042/bj1990581.

DOI:10.1042/bj1990581

PMID:7340820

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1163413/

Abstract

Two proteodermatan sulphate species from bovine sclera (fractions PG-I and PG-II) separable by gel chromatography were studied by isopycnic centrifugations in CsCl and Cs(2)SO(4) both in an analytical and a preparative mode. 2. In CsCl, fraction PG-I formed a broad band at a density rho=1.75g/ml whereas fraction PG-II banded sharply at rho=1.64g/ml. However, in Cs(2)SO(4), fraction PG-II banded at rho=1.51g/ml and fraction PG-I at rho=1.40g/ml, a reversal of the relative banding positions of the two species in CsCl. 3. Preparative isopycnic centrifugations in the two caesium salts permitted further subfractionation of fractions PG-I and PG-II. In both CsCl and Cs(2)SO(4) fraction PG-I was split into subfractions that varied greatly in uronate/protein ratios but had very similar uronate composition. In contrast, isopycnic centrifugation of fraction PG-II in Cs(2)SO(4) gave rise to subfractions with similar uronate/protein ratios but markedly different uronate composition (iduronate content, 88-42%). 4. Subfractions of fractions PG-I and PG-II obtained in preparative centrifugations in CsCl or Cs(2)SO(4) were examined in the analytical ultracentrifuge. These subfractions banded at discrete positions in the gradient. Estimations of apparent molecular weight for these subfractions from data from the analytical isopycnic centrifugations gave values that were much higher (around 1x10(6)) than were those obtained previously for their ;monomeric' states (fraction PG-I 160000-410000, and fraction PG-II 70000-130000). 5. In CsCl, fraction PG-I may be subfractionated according to the number of side chains in the molecule. Fraction PG-I increased its net solvation (i.e. lowered its buoyant density) to a larger extent than did fraction PG-II in going from CsCl to Cs(2)SO(4) (i.e. from lower to higher water activity). It is proposed that the presence of large amounts of iduronate in fraction PG-II makes these molecules relatively less solvated in Cs(2)SO(4). Thus the uronate composition may be an important factor in determining the banding position of proteodermatan sulphates in density-gradient centrifugations.

摘要

对通过凝胶色谱法可分离的来自牛巩膜的两种硫酸皮肤素（PG-I和PG-II级分），采用氯化铯和硫酸铯进行等密度离心，以分析和制备两种模式进行研究。2. 在氯化铯中，PG-I级分在密度ρ = 1.75g/ml处形成一条宽带，而PG-II级分在ρ = 1.64g/ml处形成狭窄条带。然而，在硫酸铯中，PG-II级分在ρ = 1.51g/ml处条带，PG-I级分在ρ = 1.40g/ml处条带，这与两种级分在氯化铯中的相对条带位置相反。3. 在两种铯盐中进行制备性等密度离心可对PG-I和PG-II级分进一步细分。在氯化铯和硫酸铯中，PG-I级分均被细分为糖醛酸/蛋白质比率差异很大但糖醛酸组成非常相似的亚级分。相反，PG-II级分在硫酸铯中的等密度离心产生了糖醛酸/蛋白质比率相似但糖醛酸组成明显不同（艾杜糖醛酸含量为88 - 42%）的亚级分。4. 对在氯化铯或硫酸铯中进行制备性离心得到的PG-I和PG-II级分的亚级分进行分析超速离心检测。这些亚级分在梯度中位于离散位置。根据分析性等密度离心数据估算这些亚级分的表观分子量，得到的值比之前其“单体”状态的值（PG-I级分160000 - 410000，PG-II级分70000 - 130000）高得多（约为1×10⁶）。5. 在氯化铯中，PG-I级分可根据分子中侧链的数量进行细分。从氯化铯到硫酸铯（即从较低到较高水活性）时，PG-I级分比PG-II级分在更大程度上增加其净溶剂化作用（即降低其浮力密度）。有人提出，PG-II级分中大量艾杜糖醛酸的存在使这些分子在硫酸铯中相对溶剂化程度较低。因此，糖醛酸组成可能是决定硫酸皮肤素在密度梯度离心中条带位置的一个重要因素。