IsoChichibabin desmosine-13C3,15N1 synthesis and quantitative LC-MS/MS analysis of desmosine and isodesmosine in human skin
Mika Hirose, Toyoaki Kobayashi, Nao Tanaka, Ayame Mikagi, Hiroshi Wachi, Yuki Mizutani, Toyonobu Usuki
Abstract
Desmosine and isodesmosine are crosslinking amino acids of elastin , which is an essential component of the dermal extracellular matrix protein . Quantitative analysis of crosslinker desmosines in human skin dermis has not been fully achieved due to the insoluble nature of elastin protein. In the present study, chemical synthesis of isotopically labeled desmosine, desmosine- 13 C 3 , 15 N 1 , was carried out via isoChichibabin pyridinium synthesis starting from corresponding isotopically labeled amino acids . Isotope-dilution LC-MS/MS analysis of desmosine and isodesmosine utilizing synthetic desmosine- 13 C 3 , 15 N 1 enabled the quantitative analysis of desmosines in human skin for the first time. Thus, ca. 1.43 μg of desmosines was detected from analysis of 1 mg of dry human skin.