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Determination of plasma pyridoxal 5′-phosphate by an enzymatic-high-performance liquid chromatographic procedure

1989; Elsevier BV; Volume: 181; Issue: 2 Linguagem: Inglês

10.1016/0003-2697(89)90241-8

1096-0309

Peter H. Yu,

Protein purification and stability

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.