Showing 2 results for Phenylalanine Dehydrogenase (phedh)
Eskandar Omidinia, Heshmatollah Taherkhani, Yasuhisa Asano, Shohreh Khathami, Alireza Omumi, Ata-Allah Ghadiri, Daniel van der Lelie, Roya Rashidpouraie, Hassan Mirzahoseini, Abbas Samadi,
Volume 6, Issue 1 (1-2002)
Abstract
Cloning and expression of the L-phenylalanine dehydrogenase gene, from B. sphaericus in E. coli were done. The gene was cloned in the vector pET16b and transformed into E. coli BL21 (DE3). The functional form of the L-phenylalanine dehydrogenase enzyme was purified by affinity purification techniques, taking advantage of the ability of this enzyme to bind to the nucleotide site affinity dye, Reactive Blue 4. Approximately 3 mg of highly purified recombinant enzyme was obtained from 950 mg cell pellet (wet weight). The Relative molecular mass of the L-phenylalanine subunits was about 41 kDa by 10% SDS-PAGE. Using this method, the enzyme was obtained with a yield of 28%, and had a specific activity of 577.3 U/mg protein, which is purified 88 times. This method was provided a facile and effective way for preparing the enzyme with a good yield that suitable for analytical purposes.
Hamid Shahbaz Mohammadi, Eskandar Omidinia, Heshmatollah Taherkhani,
Volume 12, Issue 2 (4-2008)
Abstract
Background: Phenylalanine dehydrogenase (PheDH EC 1.4.1.20) is a NAD+-dependent enzyme that performs the reversible oxidative deamination of L-phenylalanine to phenylpyruvate. It plays an important role in detection and screening of phenylketonuria (PKU) diseases and production of chiral intermediates as well. The main goal of this study was to find a simple and rapid alternative method for purifying PheDH. Methods: The purification of recombinant Bacillus sphaericus PheDH was investigated in polyethylene glycol (PEG) and ammonium sulfate aqueous two-phase systems (ATPS). The influences of system parameters including PEG molecular weight and concentration, pH and (NH4)2SO4 concentration on enzyme partitioning were also studied. The purity of enzyme was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Results: A single extraction process was developed for separation and purification of recombinant PheDH from E. coli BL21 (DE3). The optimized conditions for partitioning and purification of PheDH were 9% (w/w) PEG-6,000 and 16% (w/w) (NH4)2SO4 at pH 8.0. The partition coefficient, recovery, yield, purification factor and specific activity values were achieved 58.7, 135%, 94.42%, 491.93 and 9828.88 U/mg, respectively. Also, the Km values for L-phenylalanine and NAD+ in oxidative deamination were 0.21 and 0.13 mM, respectively. Conclusion: The data presented in this paper demonstrated the potential of ATPS as a versatile and scaleable process for downstream processing of recombinant PheDH.
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