Effects of ultraviolet light on free and peptide-bound pyridinoline and deoxypyridinoline cross-links. Protective effect of acid pH against photolytic degradation

Citation
B. Meddah et al., Effects of ultraviolet light on free and peptide-bound pyridinoline and deoxypyridinoline cross-links. Protective effect of acid pH against photolytic degradation, J PHOTOCH B, 54(2-3), 2000, pp. 168-174
Citations number
28
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY
ISSN journal
10111344 → ACNP
Volume
54
Issue
2-3
Year of publication
2000
Pages
168 - 174
Database
ISI
SICI code
1011-1344(200002)54:2-3<168:EOULOF>2.0.ZU;2-U
Abstract
Little is known about the photodegradation of pyridinoline (Pyd) and deoxyp yridinoline (Dpd) which are two mature cross-links stabilizing collagen wit hin extracellular matrix. In this study, highly purified free Pyd and Dpd c ross-links have been degraded by irradiation with ultraviolet light and we have shown that photolysis varies with the FH value. Assessment of photolys is in basic (pH 9) and neutral (pH 7) solutions by high-performance liquid chromatography as well as by UV absorbance measurement indicates that both cross-links are degraded after a 24 h UV exposure, while in acidic solution (pH 3) only Dpd is photolysed, suggesting that acid pH provides major prot ection against Pyd photolysis. Photodegradation products have been studied by amino-acid and mass spectral analysis. Both methods confirm the lack of Pyd degradation in acid pH. Furthermore, amino-acid analysis allows us to i dentify hydroxylysine and lysine as a result of Pyd and Dpd photolysis, res pectively, indicating that the mechanism of photodegradation involves the c leavage of the pyridinium ring on each side of the quaternary nitrogen. Fin ally, we have also studied the photolysis of different molecular species of type I collagen peptides, obtained by digestion with collagenase of demine ralized turkey bone. Our results indicate that even when they are part of t he structure of collagen peptide, Pyd and Dpd can be photolysed. However, w e have shown that the larger the peptide is, the smaller are the effects of UV irradiation. (C) 2000 Elsevier Science S.A. All rights reserved.