Effect of ultraviolet radiation on photodegradation of collagen

Abstract

Photodegradation of solvent-cast collagen type I films and photostabilization of collagen by vitamin E were studied. These films were exposed to polychromatic radiation from a medium-pressure mercury lamp or monochromatic radiation from the Okazaki Large Spectrograph (OLS). Changes in the molecular structure of collagen were followed by UV-visible and FTIR spectroscopic measurements. Electron spin resonance (ESR) spectroscopic measurements were also carried out to identify the reaction intermediates of photodegradation. Photoreaction from phenylalanine, which is one of the main constituents of collagen to tyrosine and the scission of peptide linkage of collagen, were confirmed. Vitamin E was found to be an efficient photostabilizer for photodegradation of collagen. Action spectra of photodegradation and photostabilization of a collagen molecule were reported. A possible mechanism for the photodegradation of the collagen and photostabilization scheme based on these experimental results are presented.

Surface properties of UV-irradiated poly(vinyl alcohol) films containing small amount of collagen

“…In PVA the action of UV-irradiation causes mainly degradation [18], whereas in collagen it causes mainly conformational transformation (helix-coil transition) [19][20][21].…”

Thermal denaturation of UV-irradiated wet rat tail tendon collagen

“…It has been reported that the process of UV irradiation can induce crosslinks into collagen fibrils. However, this is complicated by peptide bond scission events that may also occur through free radical mechanisms [12][13][14][15][16]. The photochemical reactions may be attributed to direct absorption by tyrosine/phenylalanine or to peptide bonds [12,13].…”

Bioactive Assessment and Bacteria Test for the Varied Degrees of Ultra-Violet Radiation Onto the Collagen-Immobilized Polypropylene Non-Woven Fabric

“…It is reported that purified collagen, in the form of powder or solution, may increase insoluble fraction by additive or photo-crosslinking reactions. It is also supported that degradation of collagen results from denaturation of triple helix structure, which also provokes the decay of collagen's bioactivity [15,17,21]. The structural damage of collagen has been widely re ported as turning phenylalanine into tyrosine (struc tural scission of-OH) [17,22], decarboxylation (struc tural scission of-C=0) [17,22,23], hydrogen abstrac tion (structural scission of-N-H) [17,23,24], thermal denaturation [18,[25][26], and general oxidative degra dation [ 17,18,[23][24][25].…”

“…Collagen has a supercoiled triple helix conforma tion and is sensible to different degrees of radiation [15][16][17][18][19][20]. It is reported that purified collagen, in the form of powder or solution, may increase insoluble fraction by additive or photo-crosslinking reactions.…”