Mass spectrometric analysis of Collagen alpha-1 (II) chain from Capra hircus

Expressional alterations and post translational modifications (PTM) of type II collagen can be major cause behind osteo and rheumatoid arthritis. PTM of type II collagen α1 chain (COL2A1) such as hydroxylation of proline (P), lysine and glycosylation of hydroxylysine can act as epitopes resulting COL2A1 as autoantigen in cartilage tissues. Previous study stated proline hydroxylation (Hyp) as an important PTM in type II collagen leading to dysfunctional collagen extracellular matrix assembly in vivo. Here we report for the first time peptide mass fingerprinting (PMF) identification and tandem mass spectrometry based mapping of Hyp PTM in COL2A1 from Capra hircus (C. hircus) using Mascot database. As mascot database does not contain C. hircus COL2A1 sequence information, our identification is based on the homologous COL2A1 from Bos taurus and Homo sapience (above 98 % identity). Findings include identification of new triplet Gly-F-Hyp in C. hircus COL2A1 and well known Gly-X-Y triplet with Hyp present in the X position, instead of Y position. PMF data contains lager number of Hyp in COL2A1 from C. hircus consistent with other collagen sequences. This study suggests positional alteration of Hyp/P in Gly-X-Y triplet may be used for molecular identification and characterization of type II collagen from other sources.