Between the aggregated and in tissues properly deposited collagen molecules crosslinking elements, e.g. pyridinoline and deoxy-pyridinoline, are enzymatically formed. These triple-functional crosslinks are located at specific sites of the collagen chains, bind covalently its molecules, and contribute to the stability of collagen structure. Analogical quadruple-functional crosslinks are formed in the elastin, i.e. desmosine and isodesmosine, which have essential physiological functions in the body. When either collagen or elastin becomes resorbed, all the crossling elements are released into blood, and they concentrate in urine. Assessment of these elements in the body fluids can be used as an indicator of the disintegration kinetics of both tissues. Practically in all long-living tissues of the organism, a cascade of non-enzymatic chemical reactions between reducing sugars and free amino-groups generates the so-called AGE-derivatives. This family of substances, represented by pentosidine, acts in the body exclusively negatively. Their determination in tissues and in body fluids represents important markers in the clinical investigation of various diseases. The possible mechanisms of the enzymatically and non-enzymatically formed crosslinks are discussed, and the relation of AGE-derivatives to various diagnostical findings is mentioned.

Revmatologický ústav Praha