Shriners Hospitals for Children, Portland, OR, USA.
Connect Tissue Res. 2013;54(1):41-8. doi: 10.3109/03008207.2012.734876. Epub 2012 Dec 3.
The triple-helical domains of two subtypes of type V collagen were prepared from human placenta, one with the chain composition of α1(V)α2(V) (Vp112) and the other with the chain composition of α1(V)α2(V)α3(V) (Vp123) with limited pepsin treatment. In order to characterize the triple-helical domain of the type Vp123 collagen molecule, the reconstituted aggregate structure formed from the pepsin-treated collagen was compared by using transmission electron microscopy. The diameter of the fibrils reconstituted from types pepsin-treated type Vp123 collagen and type Vp112 collagen was highly uniform and less than the D-periodicity at all the temperatures examined, suggesting that the major triple-helical domain of both subtypes has a potency to limit their lateral growth. Both fibrils were approximately 45 nm in width and showed the D-periodic banding pattern along their axes at 34°C. In contrast to type Vp112, the reconstituted type Vp123 fibrils showed no banding pattern along their axes when they were reconstituted at 37°C. The banded fibrils once reconstituted from type Vp123 at 34°C tend to lose their characteristic pattern within 60 min when they were incubated at 37°C. One explanation is that a slightly higher content of hydrophobic residues of type Vp123 collagen than those of type V112p collagen augmented the intermolecular interaction that disturbs the D-periodicity governed essentially by electrostatic interactions. Taken together with recent data in Col5a3 gene-targeted mice, the results suggest that type V123 collagen exists not only as a periodic banded fibril but also as nonfibrillar meshwork structures.
两种类型 V 胶原的三螺旋结构域由人胎盘制备，一种具有 [α1(V)]2α2(V)（Vp112）的链组成，另一种具有 α1(V)α2(V)α3(V)（Vp123）的链组成，用胃蛋白酶处理有限。为了表征 Vp123 胶原分子的三螺旋结构域，使用透射电子显微镜比较了胃蛋白酶处理后的胶原重新形成的聚合体结构。从胃蛋白酶处理的 Vp123 型和 Vp112 型胶原重建的原纤维的直径在所有检查温度下均高度均匀且小于 D 周期性，表明两种亚型的主要三螺旋结构域均具有限制其侧向生长的能力。两种原纤维的宽度均约为 45nm，并在 34°C 时沿其轴显示出 D 周期性带纹图案。与 Vp112 型不同，在 37°C 时重新组装的 Vp123 型原纤维沿其轴没有带纹图案。在 34°C 从 Vp123 型重新组装的带纹原纤维在 37°C 孵育时，其特征图案在 60 分钟内容易丢失。一种解释是，Vp123 型胶原的疏水性残基含量略高于 V112p 型胶原，这增加了干扰由静电相互作用基本控制的 D 周期性的分子间相互作用。结合 Col5a3 基因靶向小鼠的最新数据，结果表明 Vp123 型胶原不仅存在周期性带纹原纤维，还存在非纤维状网状结构。
