The present invention relates to a method for providing information for the diagnosis and/or prognosis of aortic valve stenosis, and was arrived at by discovering that an increase in anti-citrullinated peptide antibody levels is associated with the onset and prognosis of aortic valve stenosis. The present inventors discovered that the accurate early diagnosis of aortic valve stenosis is possible through measuring anti-citrullinated peptide antibody levels, and the degree of aortic valve deformity, severity, and probability of complications such as hypertension, rheumatoid arthritis, and interstitial lung disease can be predicted, and thus the anti-citrullinated peptide antibody is expected to be used as a biomarker for more effective diagnosis, prognosis, and treatment of aortic valve stenosis.

The present invention provides phenylglyoxal-based alkyne (PGA) chemical tags exhibiting high specificity towards protein citrullination sites and other biomolecules containing similarly reactive functional groups. The PGA tags are able to bind to or derivatize biomolecules, such as polypeptides having one or more post-translational modifications (PTMs), such as citrullination. In particular, the PGA tags of the present invention have superior reactivity and selectivity towards ureido groups, and allow for the analysis of biomolecules containing ureido groups facilitated by click chemistry and mass spectrometry (MS) techniques and methods for qualitative and quantitative analysis of biological and clinical samples.