Mechanisms of the influence of UV irradiation on collagen and collagen‐ascorbic acid solutions

Abstract

The study of the influence of UV irradiation on collagen solutions has shown the destabilization of the collagen molecule by calorimetric method. It is reflected both in changes of thermodynamic parameters of transition (Tm,ΔH,Cp=f(t)) and in the appearance of a low temperature peak, that is practically irreversible against rescanning. All these indicate that the important defects in the molecule occur. The ESR measurements have shown that the above-mentioned thermal changes are connected with the occurrence of free radicals in solution under UV irradiation. They interact with proline (Pro) residues of the protein with the appearance of secondary free radicals, with following migration to glycine (Gly) residues. The emergence of the free radicals at the Pro and then at the Gly residues may cause the dramatic structural defect resulting from the UV irradiation, which significantly alters the network of hydrogen bonds in the triple helix of the collagen molecule. All this is connected with destabilization of the collagen molecule, because the defects in amino acid residues probably lead to cleavage of covalent bonds near the damaged sites maintaining the triple helical structure. The presence of ascorbic acid in collagen solution protects the collagen molecule from occurring of secondary free radicals.

Studies on the effects of mixed light-thermal ageing on parchment by vibrational spectroscopy and micro hot table method

“…The main focus of this work was a systematic study of photo-oxidative deterioration of parchment provoked by sunlight irradiation. The photochemistry of pure collagen in aqueous solution, powder and film was already been extensively studied [18][19][20][21][22][23][24][25][26][27][28]. Photo-oxidation due to UV irradiation can cause structural damage of collagen molecules by weakening and cleaving the covalent bonds near the amino acid residues (i.e.…”

“…Photo-oxidation due to UV irradiation can cause structural damage of collagen molecules by weakening and cleaving the covalent bonds near the amino acid residues (i.e. proline) in the single chain [22,23]. As described in 1994 by Feller [24], the chemical bonds at the Cα atom are split by the free radicals formed by the UV irradiation and thus the fragmentation of the molecule is promoted.…”

Physical crosslinkings of edible collagen casing

“…Physical crosslinkings, such as ultraviolet (UV) irradiation and dehydrothermal treatment (DHT) are usually believed to be safe and effective for bio-polymerization [15,16]. UV irradiation, belonging to a form of non-ionizing electromagnetic radiation, has http://dx.doi.org/10.1016/j.ijbiomac.2015.09.032 0141-8130/© 2015 Elsevier B.V. All rights reserved.…”

Uv damage of collagen: Insights from model collagen peptides

“…There are many studies from different laboratories characterizing the collagen oxidative damage as a result of UV radiation 8, 11–20. The most widespread hypothesis is that collagen peptide bonds are cleaved randomly by UV without disrupting the triple helical structure 8.…”