Comper W D, Preston B N
Biochem J. 1974 Oct;143(1):1-9. doi: 10.1042/bj1430001.
The osmotic pressure of solutions of sulphated proteoglycans isolated from the intervertebral discs of animals of various ages was determined. The behaviour of the solutions in salt-added systems was investigated in terms of the Donnan distribution of the mobile ions. It is evident that this effect is the dominating factor in explaining the observed nonidealities. Although marked variations in the compositions of the proteoglycan, with regard to their chondroitin sulphate and keratan sulphate content and hence charge content, occur with increasing age of parent tissue, the osmotic activities of the various preparations are very similar. This is explained by the ;fixation' of the counterions in such a way as to counteract any change in the charge content of the polyion; an ;osmotic buffering' effect. The swelling behaviour of gelatin gels containing the proteoglycan preparations has been measured. In all cases pressures in excess of the sum of the osmotic pressures of the individual components are observed. However, the magnitude of the excess decreases with increasing age of the parent tissue. It is suggested that the age changes, as reflected by a decrease in water content of the gel system, are not the result of changes in the osmotic properties of the individual components but rather reflect changes in the entropic interaction of the proteoglycan with the gelatin matrix. The relevance of this observation to the situation in vivo is discussed.
测定了从不同年龄动物的椎间盘中分离出的硫酸化蛋白聚糖溶液的渗透压。根据可移动离子的唐南分布，研究了加盐体系中溶液的行为。显然，这种效应是解释所观察到的非理想性的主导因素。尽管随着母体组织年龄的增加，蛋白聚糖的组成在硫酸软骨素和硫酸角质素含量以及电荷含量方面有明显变化，但各种制剂的渗透活性非常相似。这可以通过抗衡离子的“固定”来解释，即抗衡聚离子电荷含量的任何变化；一种“渗透缓冲”效应。测量了含有蛋白聚糖制剂的明胶凝胶的溶胀行为。在所有情况下，都观察到压力超过了各个组分渗透压之和。然而，过量的程度随着母体组织年龄的增加而降低。有人提出，凝胶体系含水量的降低所反映的年龄变化，不是各个组分渗透性质变化的结果，而是反映了蛋白聚糖与明胶基质熵相互作用的变化。讨论了这一观察结果与体内情况的相关性。
