The importance of minor collagenous chains in the articular cartilage

This is a review of the present knowledge on the newly-described minor cartilage collagens. The authors deal with the nomenclature, methodology, structure and function of the minor collagens based on both literary data and their own results. The authors were the first to describe the occurrence of minor collagens in adult human articular cartilage and the change of the minor collagen content with age and osteoarthrosis [25]. The methods used by different groups for fractionation of minor collagens are different. As the recommended pepsin digestion used for solubilization of these collagens gives different results for the size of one of the minor collagens called M-collagen, special attention should devoted to the method used. The differential salt fractionation of pepsin-solubilized collagen was found the best. In this case the molecular structure of the M-collagen remained intact. In the neutral salt extraction technique recommended recently by Burgeson et al. [5], yield of collagen from sample is high, M-collagen is degraded. The greatest solubilization of collagen was achieved by the cyanogen bromide technique. The mixture of peptides from different proteins, however, requires further fractionation. The authors propose to investigate minor collagens in tissue samples obtained from biopsies and in synovial fluid.