Lenaers A, Lapiere C M
Biochim Biophys Acta. 1975 Jul 21;400(1):121-31. doi: 10.1016/0005-2795(75)90132-4.
A form of collagen, containing three alpha chains of type III, can be extracted from foetal calf, calf and rat skin under physiological conditions. This native collagen was purified by DEAE-cellulose chromatography and then was analysed by polyacrylamide gel electrophoresis which showed it consisted of several high molecular weight components, the size of gamma components and larger species. Prior reduction in dithiothreitol dissociated these large polymers into two components: the minor one migrated between the alpha1 (I) and alpha2 chains while the predominant one migrated between the alpha and beta chains. These two monomers were isolated by CM-cellulose chromatography. The minor one, which eluted between the alpha1 and alpha2 chains, had a molecular weight of approx. 95 000; its amino acid composition was similar to that of alpha1(III). The major one eluted in the alpha1 region and had a molecular weight of approx. 120 000; its amino acid composition, while similar to that of the alpha1(III) chain, differed in detail, and it is presumed to be a pro-alpha1(III) chain. Following pepsin digestion, the native collagen remained as a disulfide-bonded trimer which dissociated into only one component, a1(III), when denatured in dithiothreitol. These results suggest that the original, extracted protein consisted primarily ofa precursor form of type III collagen. This procollagen did not polymerize when heated at 37 degrees C and did not form the usual segment long spacing aggregates under suitable conditions. It was not modified by incubation with a purified procollagen peptidase preparation. This appears to be the first example of the isolation of type III (pro)collagen by extractive methods, without resorting to tissue digestion by proteolytic enzymes.
一种含有三条III型α链的胶原蛋白，可在生理条件下从胎牛、小牛和大鼠皮肤中提取。这种天然胶原蛋白通过DEAE-纤维素色谱法纯化，然后通过聚丙烯酰胺凝胶电泳分析，结果显示它由几种高分子量成分组成，即γ成分和更大的种类。在二硫苏糖醇中预先还原会使这些大聚合物解离成两个成分：较小的一个在α1（I）和α2链之间迁移，而主要的一个在α链和β链之间迁移。这两种单体通过CM-纤维素色谱法分离。在α1和α2链之间洗脱的较小单体分子量约为95000；其氨基酸组成与α1（III）相似。主要单体在α1区域洗脱，分子量约为120000；其氨基酸组成虽然与α1（III）链相似，但细节上有所不同，推测为前α1（III）链。用胃蛋白酶消化后，天然胶原蛋白仍为二硫键连接的三聚体，在二硫苏糖醇中变性时仅解离成一个成分α1（III）。这些结果表明，最初提取的蛋白质主要由III型胶原蛋白的前体形式组成。这种前胶原蛋白在37℃加热时不会聚合，在合适条件下也不会形成通常的段长间距聚集体。用纯化的前胶原蛋白肽酶制剂孵育也不会对其进行修饰。这似乎是通过提取方法分离III型（前）胶原蛋白的第一个例子，而无需借助蛋白水解酶对组织进行消化。
