BIOLUMINESCENT FLOW SENSOR FOR L-PHENYLALANINE DETERMINATION IN SERUM

A highly sensitive and rapid bioluminescent flow sensor was developed for the determination of the content of L-phenylalanine (Phe) in serum by monitoring the reduced form of nicotinamide adenine dinucleotide ( NADH), produced by immobilized phenylalanine dehydrogenase (PheDH), wi th bacterial bioluminescent enzymes immobilized on a separate nylon co il. The L-PheDHs extracted from Bacillus badius, Bacillus sphaericus a nd Rhodococcus sp. M4 were investigated and the performances of the th ree immobilized L-PheDH's were analysed. The B. badius reactor was fou nd to give higher transformation rate and better sensitivity; the resp onse was linear from 1 to 100muM at 25-degrees, with a detection limit of 10 pmoles (0.5muM). The intra- and inter-assay coefficients of var iation were less than 5% and recoveries ranged from 90 to 101%. The re sults agreed well with those obtained with a chromatographic method fo r the Phe determination in serum and with the normal reference values.