A method for identifying and quantifying peptides resulting from enzyme cleavage of collagen type II by mass spectrometric analysis to detect characteristic peptide fragments of a carboxy-terminus having known mass to charge ratios to identify the peptide having that carboxy-terminus. Identification and quantification of the peptides in a biological sample is used to assess activity of proteolytic enzymes in diseases or physiological conditions such as osteoarthritis and rheumatoid arthritis and to assess the efficacy of enzyme blocking agents.
