[Natural polymers according to NMR data: cross-relaxation in hydrated collagen macromolecules from two connective tissues].
Spin-lattice relaxation and cross-relaxation in oriented and randomly oriented collagen fibers from two connective tissues (15-month-old calf and 8-year-old steer) at a water content of 0.6 g H2O/g dry matter were studied. Collagens were chosen according to different numbers of covalent nonreducible cross-links, which increase during the life of the animal. The spin-lattice relaxation curves for all the collagens after a 180 degree-tau-90 degree pulse sequence were described by two exponential components. The dependences of two components of spin lattice relaxation time and their populations on the length of the 180 degree-pulse were obtained. On the basis of data of Goldman-Shen sequence and the two-phase model, the populations of proton fractions (p(w) and p(c)) as well as the rates of transfer of magnetization between water protons and collagen protons (k(w) and k(c)) were calculated. No significant difference between k(w) (k(c)) in oriented and randomly oriented fibers as well as in fibers with different cross-linking was found. The estimates of the cross-relaxation times for low cross-link collagen and high cross-link one were done. The correlation times of dipole-dipole interactions for both connective tissues were calculated using the cross-relaxation theory.
Rodin
V V
VV
Foucat
L
L
Renou
J P
JP
D000818:Animals; D002417:Cattle; D003094:Collagen / Q000737:chemistry*; D003238:Connective Tissue / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008297:Male
D003094:Collagen