Determination of plasma pyridoxal 5'-phosphate by an enzymatic-high-performance liquid chromatographic procedure.
An enzymatic-HPLC procedure for the determination of plasma pyridoxal 5'-phosphate (PLP) has been established. The assay is based on the decarboxylation of L-3,4-dihydroxyphenylalanine using Streptococcus tyrosine decarboxylase apoenzyme, which requires PLP as cofactor. The product of the enzyme reaction, dopamine, is measured by Coulochem electrochemical detection with a series of oxidizing and then reducing electrodes. Trace amounts of PLP in the apoenzyme preparation were removed with the aid of cysteine-sulfinic acid and gel filtration. The detection limit for PLP by this method is 50 pM in plasma.
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Neuropsychiatric Research Unit, University of Saskatchewan, Saskatoon, Canada.
D002851:Chromatography, High Pressure Liquid; D003866:Depressive Disorder / Q000097:blood / Q000188:drug therapy; D004032:Diet; D006801:Humans; D007980:Levodopa / Q000378:metabolism; D010624:Phenelzine / Q000009:adverse effects / Q000627:therapeutic use; D011732:Pyridoxal Phosphate / Q000097:blood*; D013291:Streptococcus / Q000201:enzymology
D007980:Levodopa; D011732:Pyridoxal Phosphate; D010624:Phenelzine