MECHANISM OF NUCLEATION FOR INVITRO COLLAGEN FIBRIL FORMATION
MECHANISM OF NUCLEATION FOR INVITRO COLLAGEN FIBRIL FORMATION
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DOI：
10.1002/bip.1977.360161004
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发表时间：
1977-01-01
期刊：
影响因子：
2.9
通讯作者：
VEIS, A
中科院分区：
文献类型：
--
作者：
COMPER, WD;VEIS, A
在中性pH下，由可溶性单体和聚集体形成胶原蛋白的原纤维可分为2个不同的阶段：成核期和生长期。沉淀反应动力学的浊度研究表明，滞后相时间或成核反应时间t' l明显依赖于温度，而生长反应在研究的温度范围内基本不变。在用各种物理化学技术（包括粘度、沉降平衡和光散射）监测成核相反应时，没有观察到聚集体形成的证据。用聚集物富集初始胶原溶液加速成核，但即使在高度聚集的胶原制备中，仍需要重新形成细胞核。去除胃蛋白酶和pronase敏感肽延长了成核反应时间，增加了核形成速率对离子强度变化的敏感性。电镜研究表明，由蛋白酶处理的胶原蛋白形成的原纤维组织不太好。在胃蛋白酶处理的胶原中，可以看到亚原纤维和斜纹原纤维，这表明当形成微原纤维时，它们之间的相互作用受到酶敏感肽的调节，就像这些区域调节细胞核组装一样。胶原蛋白的胃蛋白酶和pronase敏感肽区显然比螺旋分子区之间的离子相互作用在胶原分子体外组装形成d -交错核和原纤维中发挥更突出的作用。讨论了胶原纤维形成的成核机制。
The formation of collagen [from rat skin] fibrils from soluble monomers and aggregates by thermal gelation at neutral pH can be divided into 2 distinct stages: a nucleation phase and a growth phase. Turbidity studies of the kinetics of the precipitation reaction show that the lag-phase time or nucleation reaction time, t''l, is markedly temperature dependent while the growth reaction is essentially constant over the temperature range studied. In monitoring the nucleation-phase reaction by various physicochemical techniques, including viscosity, sedimentation equilibrium and light scattering, no evidence for the formation of aggregates was observed. Enrichment of the initial collagen solution with aggregates accelerates nucleation, but de novo nuclei formation is still required even in highly aggregated collagen preparations. Removal of pepsin and pronase susceptible peptides lengthens the nucleation reaction time and increases the sensitivity of the rate of nuclei formation to changes in ionic strength. EM studies show the fibrils formed from the protease-treated collagen to be less well organized. With pepsin-treated collagen, subfibrils and obliquely striated fibrils are seen, showing that while microfibrils are formed interactions between them are modulated by the enzyme susceptible peptides in the same way that these regions modulate nuclei assembly. Pepsin and pronase susceptible peptide regions of collagen apparently play a more prominent role in the in vitro assembly of collagen molecules to form D-stagger nuclei and fibrils than do ionic interactions between helical molecular regions. A mechanism of nucleation of collagen fibrillogenesis is discussed.