• Korean Journal of Microbiology
• /
• v.45 no.2
• /
• pp.200-207
• /
• 2009

In this study, the characterization of purified erythritol 4-phosphate dehydrogenase, key enzyme of erythritol biosynthesis, produced by Penicillium sp. KJ81 was investigated. Optimum production conditions of erythritol 4-phosphate dehydrogenase was 1 vvm areration, 200 rpm agitation, at $37^{\circ}C$ for 8 days in the medium containing 30% sucrose, 0.5% yeast extract, 0.5% $(NH_4)_2SO_4$, 0.1% $KH_2PO_4$, and 0.05%$MgCl_2$. Erythritol 4-phosphate dehydrogenase was purified through ultrafiltration and preparative gel electrophoresis from cell extract of Penicillium sp. KJ81. This enzyme was especially active on erythrose 4-phosphate with 1.07 mM of Km value. It gave a single band on native polyacrylamide gel electrophoresis and an isoelectric point of 4.6. The enzyme had an optimal activity at pH 7.0 and $30^{\circ}C$. It was stable between pH 4.0 and 9.0, and also below $30^{\circ}C$. The enzyme activity was completely inhibited by 1mM $Cu^{2+}$ and 1 mM $Zn^{2+}$, but was not significantly affected by other cations tested. This enzyme was inactivated by treatment of tyrosine specific reagent, iodine and tryptophan specific reagent, N-bromosuccinimide. The substrate of the enzyme, erythrose 4-phosphate showed protective effect on the inactivation of the enzyme by both reagents. These results suggest that tryptophan and tyrosine residues are probably located at or near active site of the enzyme.