A method for quantitative analysis of ratios of types I and II collagen in small samples of articular cartilage

Currently available methods for quantitative analysis of type II collagen in studies of articular cartilage repair either require much larger samples than are available or are inaccurate and unreliable. A method of determining the percentage of type II collagen in small samples of articular cartilage (100 to 200 micrograms) by measuring the spectrophotometric densities of specific cyanogen bromide peptide bands from mixtures of types I and II collagen on sodium dodecyl sulfate-polyacrylamide gels has been developed and found to be accurate and very reliable. The ratio of the area under the alpha 1(II)CB10 peak to the area under the alpha 1(I)CB7,8 + alpha 1(II)CB11 peak was function of the proportion of type II collagen in the sample. Since the ratio was independent of the quantity of sample loaded onto the gel, it was not affected by moderate losses of sample. This method should therefore be useful in the fields of collagen research and particularly valuable to those investigating the repair and regeneration of articular cartilage.