Wright D M, Duance V C, Wess T J, Kielty C M, Purslow P P
The Royal Veterinary and Agricultural University, Copenhagen, Denmark, School of Biosciences, Cardiff University, Cardiff CF1 3US, UK.
J Exp Biol. 1999 Nov;202(Pt 21):3011-20. doi: 10.1242/jeb.202.21.3011.
The zonular filaments from the eyes of cows are rich in microfibrils containing fibrillin. Tensile tests, stress-relaxation tests and X-ray diffraction studies were used to study the relationship between the mechanical behaviour of zonular filaments and the molecular packing and structure of the fibrillin-rich microfibrils. Zonular filaments show a non-linear (J-shaped) stress-strain curve and appreciable stress-relaxation. It is proposed that the non-linear properties are due to local variations in waviness in the microfibrils or assemblies of microfibrils, which straighten out and become more regularly aligned with strain. Previous and current X-ray diffraction results consistently show a partial ordering of microfibrils in zonular filaments into staggered aggregates which become more ordered and laterally aligned on stretching. Although the removal and re-addition of Ca(2+) is known to change the molecular structure of fibrillin, no effect was observed on the tensile properties of the zonular filaments. It is hypothesised that strain-induced deformation in the supramolecular aggregate packing may not be Ca(2+)-sensitive but could dominate the mechanical behaviour of microfibrillar arrays in zonular filaments.
牛眼的小带纤维富含含有原纤蛋白的微原纤维。采用拉伸试验、应力松弛试验和X射线衍射研究来探讨小带纤维的力学行为与富含原纤蛋白的微原纤维的分子堆积及结构之间的关系。小带纤维呈现非线性（J形）应力-应变曲线以及明显的应力松弛现象。有人提出，非线性特性是由于微原纤维或微原纤维集合体中波纹度的局部变化所致，这些变化在应变作用下会变直并变得更加规则地排列。以往和当前的X射线衍射结果一致表明，小带纤维中的微原纤维部分排列成交错聚集体，在拉伸时会变得更加有序并横向排列。尽管已知去除和重新添加Ca(2+)会改变原纤蛋白的分子结构，但未观察到对小带纤维拉伸性能的影响。据推测，超分子聚集体堆积中的应变诱导变形可能对Ca(2+)不敏感，但可能主导小带纤维中微原纤维阵列的力学行为。
