Portland State University. Department of Biology
Date of Publication
Master of Science (M.S.) in Biology
Dihydroorotase, Clostridium oroticum
1 online resource (52 p.)
Dihydroorotase (4,5-L-dihydro-orotate amidohydrolase, EC 184.108.40.206) which catalyzes the reversible cyclization of N-carbamyl-1-aspartate toL-dihydro-orotate has been purified from orotate-grown Clostridium oroticum by a combination of streptomycin sulfate fractionation, DEAE-Sephadex chromatography, and hydroxylapatite chromatograpy. The enzyme has been shown to be omogeneous when subjected to polyacrylamide gel electrophoresis. Thin-layer gel chromatography with Sephadex G-200 indicated the enzyme to have a molecular weight of 110,000 ± 10,000. Sodium dodecyl sulfate gel electrophoresis using two different buffer systems indicate the enzyme to be composed of two identical subunits with a molecular weight of 56,000 ± 5300. Dihydroorotase has been shown to be a zinc-containing metalloenzyme by atomic absorption spectroscopy with two g atoms of zinc per 56,000 g of protein. The pH optima for the conversion of N-carbamyl-L-aspartate to L-dihydroorotate and L-dihydroorotate to N-carbamyl-L-aspartate have been determined to be at pH 6.0 and pH 8.2 respectively. The binding constant of the enzyme for each substrate has been investigated with values of 0 .13 mM for N--carbamyl-L--aspartate and .07 mM for L-dihydroorotate.
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Balch, William Edward, "Purification and characterization of dihydroorotase from Clostridium oroticum, a zinc-containing metalloenzyme" (1973). Dissertations and Theses. Paper 1690.