1996 Volume 52 Issue 11 Pages 591-597
The conformation, molecular association and staggering of the tropocollagen molecules in rat tail tendon (RTT) collagen fibril were analyzed using the small-angle X-ray-diffraction (SAXD) data. The energy calculation for the electrostatic and hydrophobic interactions was carried out on the basis of the pseudohex-agonal packing model of tropocollagens. The SAXD analysis suggested that (a) the adjacent tropocollagen molecules stagger by 234 (or 234×n, n: integer) amino acid residue length, (b) three α chains in a tropocollagen are associated such as α1-α1-α2, (c) all of telopeptide chains in α1 chains shrink, while (d) both of telopeptide regions in α2 chain fold back. The results (b), (c) and (d) were supported by the energetic viewpoint. Although the energy calculation could not determine the staggering length definitely, the 234 staggering was regarded to be most plausible, considering the high sensitivity of the SAXD method to the staggering of the chains. The shrinkage of α1 telopeptide chains and folding back of the α2 telopeptide regions were attributed to the electrostatic interaction between the telopeptides and the surrounding tropocollagen molecules.
