Measurement of plasma pyridoxal 5'-phosphate by combination of an enzymatic assay with high-performance liquid chromatography/electrochemistry.
An assay method for the determination of pyridoxal 5'-phosphate (PLP) in plasma is presented. The procedure is rapid and requires only a small volume. The method includes PLP-dependent enzymatic decarboxylation of L-tyrosine to tyramine (enzyme used: L-tyrosine apodecarboxylase (EC 4.1.1.25) from Streptococcus faecalis) and measurement of tyramine by high-performance liquid chromatography with electrochemical detection. This technique confers specificity, rapidity, and low-cost measurement. Human plasma PLP from 30 normal healthy adults had a mean value of 65.10 +/- 4.70 nM. Sensitivity of the reaction was 1.3 nM and the coefficient of variation of the method (30 repeated assays of sample with a value of 60 nM) was 1.9%.
D000328:Adult; D001051:Apoenzymes; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004563:Electrochemistry; D006801:Humans; D008297:Male; D011732:Pyridoxal Phosphate / Q000097:blood*; D012016:Reference Values; D014439:Tyramine / Q000032:analysis; D014445:Tyrosine Decarboxylase
D001051:Apoenzymes; D011732:Pyridoxal Phosphate; D014445:Tyrosine Decarboxylase; D014439:Tyramine