Grazyna Chwatko1, Hieronim Jakubowski. 1. Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, International Center for Public Health, Newark 07103, USA.
Abstract
BACKGROUND: A metabolite of homocysteine (Hcy), the thioester Hcy-thiolactone, has been implicated in coronary heart disease in humans. Because inadvertent reactions of Hcy-thiolactone with proteins can lead to cell and tissue damage, the ability to detoxify or eliminate Hcy-thiolactone is essential for biological integrity. We examined the hypothesis that the human body eliminates Hcy-thiolactone by urinary excretion. METHODS: We used a sensitive HPLC method with postcolumn derivatization and fluorescence detection to examine Hcy-thiolactone concentrations in human urine and plasma. RESULTS: We discovered a previously unknown pool of Hcy-thiolactone in human urine. Urinary concentrations of Hcy-thiolactone (11-485 nmol/L; n = 19) were approximately 100-fold higher than those in plasma (<0.1-22.6 nmol/L; n = 20). Urinary Hcy-thiolactone accounted for 2.5-28.3% of urinary total Hcy, whereas plasma Hcy-thiolactone accounted for <0.002-0.29% of plasma total Hcy. Urinary concentrations of Hcy-thiolactone, but not of total Hcy, were negatively correlated with urinary pH. Clearance of Hcy-thiolactone, relative to creatinine, was 0.21-6.96. In contrast, relative clearance of Hcy was 0.001-0.003. CONCLUSIONS: The analytical methods described here can be used to quantify Hcy-thiolactone in biological fluids. Using these methods we showed that the human body eliminates Hcy-thiolactone by urinary excretion. Our data also suggest that the protonation status of its amino group affects Hcy-thiolactone excretion.
BACKGROUND: A metabolite of homocysteine (Hcy), the thioester Hcy-thiolactone, has been implicated in coronary heart disease in humans. Because inadvertent reactions of Hcy-thiolactone with proteins can lead to cell and tissue damage, the ability to detoxify or eliminate Hcy-thiolactone is essential for biological integrity. We examined the hypothesis that the human body eliminates Hcy-thiolactone by urinary excretion. METHODS: We used a sensitive HPLC method with postcolumn derivatization and fluorescence detection to examine Hcy-thiolactone concentrations in human urine and plasma. RESULTS: We discovered a previously unknown pool of Hcy-thiolactone in human urine. Urinary concentrations of Hcy-thiolactone (11-485 nmol/L; n = 19) were approximately 100-fold higher than those in plasma (<0.1-22.6 nmol/L; n = 20). Urinary Hcy-thiolactone accounted for 2.5-28.3% of urinary total Hcy, whereas plasma Hcy-thiolactone accounted for <0.002-0.29% of plasma total Hcy. Urinary concentrations of Hcy-thiolactone, but not of total Hcy, were negatively correlated with urinary pH. Clearance of Hcy-thiolactone, relative to creatinine, was 0.21-6.96. In contrast, relative clearance of Hcy was 0.001-0.003. CONCLUSIONS: The analytical methods described here can be used to quantify Hcy-thiolactone in biological fluids. Using these methods we showed that the human body eliminates Hcy-thiolactone by urinary excretion. Our data also suggest that the protonation status of its amino group affects Hcy-thiolactone excretion.
Authors: Hieronim Jakubowski; Joanna Perla-Kaján; Richard H Finnell; Robert M Cabrera; Hong Wang; Sapna Gupta; Warren D Kruger; Jan P Kraus; Diana M Shih Journal: FASEB J Date: 2009-02-09 Impact factor: 5.191
Authors: Arther T Gates; Sayo O Fakayode; Mark Lowry; Gabriela M Ganea; Abitha Murugeshu; James W Robinson; Robert M Strongin; Isiah M Warner Journal: Langmuir Date: 2008-03-07 Impact factor: 3.882