Quantification of desmosine and isodesmosine using MALDI-ion trap tandem mass spectrometry.

Desmosine (Des) and isodesmosine (Isodes), cross-linking amino acids in the biomolecule elastin, may be used as biomarkers for various pathological conditions associated with elastin degradation. The current study presents a novel approach to quantify Des and Isodes using matrix-assisted laser desorption ionization (MALDI)-tandem mass spectrometry (MS) in a linear ion trap coupled to a vacuum MALDI source. MALDI-MS analyses of Des and Isodes are performed using stable-isotope-labeled desmosine d (labeled-Des) as an internal standard in different biological fluids, such as urine and serum.

Ultraviolet radiation reduces desmosine cross-links in elastin.

Elastic fibers, a major component of the extracellular matrix of the skin, are often exposed to ultraviolet (UV) radiation throughout mammalian life. We report on an study of the alterations in bovine nuchal ligament elastic fibers resulting from continuous UV-A exposure by the use of transmission electron microscopy (TEM), histology, mass spectrometry, and solid state C NMR methodologies. TEM images reveal distinct cracks in elastic fibers as a result of UV-A irradiation and histological measurements show a disruption in the regular array of elastic fibers present in unirradiated samples; elastic fibers appear shorter, highly fragmented, and thinner after UV-A treatment.