Effects of High Sugar, Iodine and Strain to the Packing Structure of Collagen as Revealed by X-ray Fiber Diffraction

X-ray diffraction has become a vital technique for understanding changes in molecular structures of proteins and assemblies, more so in extracellular matrix research. Particularly, it provides with a means of collecting structural data on un-fixed tissues which is of great importance when small changes in structure are under pursuit.

The process of non-enzymatic glycosylation, i.e. glycation, is rather slow resulting in the formation of sugar-mediated crosslinks, also known as Advanced Glycation Endproducts (AGEs), within the native structure of type I collagen, a predominant component of tendons and ligaments. This process occurs in all animals but is accelerated in diabetics. However, the exact locations or regions of high propensity for the formation of these crosslinks within the packing structure of collagen are largely unknown, despite our knowledge of the underlying chemistry. The results presented inform on the location of possible crosslinks to and correlate the effects of crosslinks to the structural and functional sites present on the D-periodic arrangement of collagen into fibrils.

Prolonged treatment with iodine, as a wound disinfectant, is detrimental to the structure of collagen underlying the wound site. Diabetic patients are more prone to injuries to limb extremities. Wounded extremities are commonly amputated to prevent the spread of infection to the rest of the body followed by low dose iodine application to the wound site. We present result to demonstrate specific disintegration of collagen fibrils in rat tail tendons, from a short iodine treatment.

A logical extension to the studies on tendons would be to understand the how they interact with muscles and the stress-strain relation of this system that, results in the transfer of load (motion). The muscle-tendon junction (MTJ) is one of the most complicated collagenous tissues, from a material and properties perspective. A study of changes in the molecular and macroscopic strain with the application of stretch can be of great value in improving surgical methods on tissues presenting or possessing a muscle-tendon transition, for example, heart valves, sphincters etc. Preliminary data on the “molecular” (using XRD) and macroscopic (using microscopy) stress-strain relations will be shown.