ScienceAsia 12 (1986): 127-139 |doi: 10.2306/scienceasia1513-1874.1986.12.127

SOLUBILIZATION OF GLYCOSOMAL OROTATE PHOSPHORIBOSYLTRANSFERASE AND OROTIDYLATE DECARBOXYLASE FROM CRITHIDIA LUCILIAE

SAISANOM TAMPITAG^* AND WILLIAM J. O'SULLIVAN⁺

ABSTRACT: Tightly bound glycosomal OPRTase and ODCase from Crithidia luciliae were solubilized using Triton X-1OO in the presence of cryoprotectants, dimethyl suIfoxide and glycerol. Recoveries of better than 20% for both enzymes were achieved. Properties of the solubilized enzymes which differed from those of intact glycosomal enzymes included efficiency of substrate channelling, the K_m of ODCase for OMP, heat stabilities and the activation energies obtained from Arrhenius plots. Chromatography on Sepharose CL - 6B in the presence of 0.25 M sucrose yielded a high molecular weight species containing both enzyme activities. In the presence of 0.15 M NaCI and the absence of sucrose, most of the ODCase activity eluted at a position corresponding to a molecular weight of 65,000 with minor peaks of activity associated with higher molecular weight species. OPRTase activity was not recovered.

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School of Biochemistry, University of New South Wales, P.O. Box 1, Kensington, N.S. W. 2033, Australia.

Received 2 May 1986