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Kinetics of acid-induced degradation of tetra- and dihydrobiopterin in relation to their relevance as biomarkers of endothelial function.

Biomarkers : biochemical indicators of exposure, response, and susceptibility to chemicals (2012-10-17)
Alan Mortensen, Jens Lykkesfeldt
ABSTRACT

The ratio of the nitric oxide synthase (NOS) cofactor tetrahydrobiopterin (BH(4)) to its oxidized form dihydrobiopterin (BH(2)) has been suggested as an index of endothelial dysfunction. Consequently, much effort has been put into preserving the in vivo equilibrium between these labile analytes. In the present study, we conducted a series of stability experiments in aqueous solutions and blood to identify the most appropriate way of stabilizing BH(4) and BH(2). Based on our results, we are able to recommend that blood samples are immediately stabilized with dithioerythriol and protein precipitation conducted using trichloroacetic acid (TCA).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Trichloroacetic acid, ACS reagent, ≥99.0%
Sigma-Aldrich
Trichloroacetic acid solution, 6.1 N
Sigma-Aldrich
Trichloroacetic acid, BioXtra, ≥99.0%
Sigma-Aldrich
Trichloroacetic acid, ≥99.0% (titration)
Sigma-Aldrich
Trichloroacetic acid, BioUltra, ≥99.5% (T)
Sigma-Aldrich
Trichloroacetic acid, suitable for electrophoresis, suitable for fixing solution (for IEF and PAGE gels), ≥99%
Sigma-Aldrich
Trichloroacetic acid, ACS reagent, for the determination of Fe in blood according to Heilmeyer, ≥99.5%
Sigma-Aldrich
7,8-Dihydro-L-biopterin, ≥94% (HPLC)