Mass Spectrometric Analysis of Cross-linked Amino Acids in Collagen

Cross-linking plays a critical role in determining the mechanical strength of heart collagen. Its malfunction is probably related to the occurrence of heart failure. Studies show that the content of some cross-linked amino acids can be used as biomarkers for the abnormal cross-linking of their corresponding collagens. However, it is still unclear about the biomarkers for the unusual cross-linking in heart collagen. Hence, we present in this study a tandem mass spectrometry method that enables highly selective identification of two important cross-linked amino acids, pyridinoline (PYD) and deoxypyridinoline (DPD), in hydrolyzed collagen. DPD was detected in acid-hydrolyzed mouse ventricle collagen, while PYD was not, indicating that PYD is not related to the cross-linking processes in heart collagen, but DPD plays a more significant role, so DPD might become a biomarker for heart failure. Overall, this study provides a mass-spectrometry-based method to investigate the cross-linking products in mouse heart collagen, which can also be applied to other collagens.