A CONSENSUS MODEL FOR MOLECULAR PACKING OF TYPE-I COLLAGEN

In this review, recent results from X-ray diffraction studies of tendo n are used to develop an understanding of the molecular packing of typ e I collagen in tendon fibrils. These cover the definition of the unit cell as triclinic, the lateral architecture of molecular packing in a fibril and the molecular packing topology of a structure that gives g ood agreement with X-ray diffraction data. The proposed model is a `D staggered left handed microfibril; the molecular orientation of the te lopeptides indicates that there are interconnections between microfibr ils that may explain the difficulty in isolating individual microfibri llar structures. This is the first structure that defines the absolute molecular packing of molecular segments based on II-ray diffraction d ata. These results are discussed in the light of direct and indirect e vidence relating to molecular packing such as mineralization, natural crosslink position, and biomechanical evidence. The ability of the pro posed structure to fulfill many of the structural and biochemical crit eria point towards the structure providing a basis for a consensus mod el of collagen packing, (C) 1998 Academic Press.