Determination of plasma pyridoxal 5'-phosphate by an enzymatic-high-performance liquid chromatographic procedure |
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| Authors: | P H Yu |
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| Institution: | Neuropsychiatric Research Unit, University of Saskatchewan, Saskatoon, Canada. |
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| Abstract: | 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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