Fraser R D, Parry D A
Department of Physics, Massey University, Palmerston North, New Zealand.
Int J Biol Macromol. 1996 Oct;19(3):207-11. doi: 10.1016/0141-8130(96)01129-4.
X-ray diffraction and electron microscope studies of hard keratins (e.g. claws, scales, feathers and hair) have shown that they all have a filamentous texture but that the molecular structure of the filaments in mammalian keratins is quite different from that in avian keratins. The framework of the filaments in mammalian keratin consists of two-strand coiled coils of alpha-helices whereas the framework in avian keratins is composed of beta-sheets. Reptilian hard keratins have not been studied in detail but the X-ray diffraction pattern is very similar to that obtained from avian hard keratins leading to the supposition that the framework of the filaments is also composed of beta-sheets. The present contribution describes an analysis of the sequence of a lizard claw protein using structural probes which reveal the origins of the common structural features of the filaments in avian and reptilian keratin.
对硬角蛋白（如爪子、鳞片、羽毛和毛发）的X射线衍射和电子显微镜研究表明，它们都具有丝状结构，但哺乳动物角蛋白中细丝的分子结构与鸟类角蛋白中的分子结构有很大不同。哺乳动物角蛋白中细丝的框架由α - 螺旋的双股卷曲螺旋组成，而鸟类角蛋白中的框架由β - 折叠组成。虽然尚未对爬行动物的硬角蛋白进行详细研究，但X射线衍射图谱与从鸟类硬角蛋白获得的图谱非常相似，这导致人们推测细丝的框架也由β - 折叠组成。本论文描述了对一种蜥蜴爪蛋白序列的分析，该分析使用了结构探针，揭示了鸟类和爬行动物角蛋白中细丝共同结构特征的起源。
