Determination of free desmosine in human plasma and its application in two experimental medicine studies

• Published in: Analytical biochemistry 2013-05, Vol.436 (2), p.127-136
• Main Authors: Lamerz, Jens, Friedlein, Arno, Soder, Nicole, Cutler, Paul, Döbeli, Heinz
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; amino acids; biomarkers; Biomarkers - blood; Body Mass Index; Body mass index (BMI); Body Weight; Case-Control Studies; Chemical Precipitation; Chromatography, High Pressure Liquid - methods; Chronic obstructive pulmonary disease (COPD); Desmosine; Desmosine - blood; Deuterium; disease course; drugs; elastin; ethanol; extracellular matrix; Female; high performance liquid chromatography; Human plasma; Humans; Isodesmosine - blood; Male; mass spectrometry; Mass Spectrometry - methods; medicine; Middle Aged; monitoring; patients; Pulmonary Disease, Chronic Obstructive - blood; Reference Values; Reproducibility of Results; Russia; Selected reaction monitoring (SRM); Smoking; United States
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/j.ab.2013.01.012

Elastin is one of the major extracellular matrix proteins associated with connective tissue. Its degradation leads to the liberation of the unique amino acids desmosine and isodesmosine. These have shown utility as biomarkers of elastin breakdown for disease progression, patient stratification, and drug efficacy. So far, the quantitation of desmosines in plasma is hampered by complex sample preparation. Here we demonstrate an improved and simplified procedure for detecting both free and total desmosines. The method is based on spiking with a deuterium-labeled desmosine standard, ethanol precipitation, propionylation, high-performance liquid chromatography (HPLC) separation, and selected reaction monitoring (SRM) mass spectrometry. The performance of the assay is illustrated by comparing the levels of free and total desmosines in normal healthy plasma and those from patients diagnosed with chronic obstructive pulmonary disease (COPD). A conserved ratio of 1:3 for free to total desmosine was found. The determination of free desmosine has higher accuracy than that of total desmosine; therefore, it is the method of choice when plasma volume is limiting. Finally, we show that the plasma desmosine concentration correlates with age and body mass index.