Probing non-enzymatic glycation of type I collagen: A novel approach using Raman and infrared biophotonic methods

Background: Non-enzymatic glycation is the main post-translational modification of long-life proteins observed during aging and physiopathological processes such as diabetes and atherosclerosis. Type I collagen, the major component in matrices and tissues, represents a key target of this spontaneous reaction which leads to changes in collagen biomechanical properties and by this way to tissue damages. Methods: The current study was performed on in vitro glycated type I collagens using vibrational microspectroscopies, FT-IR and Raman, to highlight spectral features related to glycation effect. Results and conclusions: We report a conservation of the triple-helical structure of type I collagen and noticeable variations in the exposure of proline upon glycation. Our data also show that the carbohydrate band can be a good spectroscopic marker of the glycation level, correlating well with the fluorescent AGEs formation with sugar addition. General significance: These non-invasive and label-free methods can shed new light on the spectral features of glycated collagens and represent an effective tool to study changes in the extracellular matrix observed in vivo during aging or on the advent of a pathological situation. (C) 2013 Elsevier B.V. All rights reserved.