Korean J Parasitol.  1989 Sep;27(3):161-170. 10.3347/kjp.1989.27.3.161.

Characterization of proteases of Toxoplasma gondii

• Choi WY
• Nam HW
• Youn JH

• KMID: 1720278
• DOI: http://doi.org/10.3347/kjp.1989.27.3.161

Abstract

The proteases of Toxoplasma gondii were purified partially and characterized for some biochemical properties including various chromatographic patterns, major catalytic classes, and conditions to promote the activity of these enzymes. When Toxoplasma extract was incubated with 3H-casein at various pH, peak hydrolysis of casein was observed at pH 6.0 and at pH 8.5. Proteases working at pH 6.0 and at pH 8.5 were purified partially by conventional methods of chromatographies of DE52 anion exchange, Sephadex G-200 gel permeation, and hydroxylapatite chromatography. Partially purified enzymes were tested by site-specific inhibitors and promotors. The protease working at pH 6.0 was inactivated by iodoacetamide with LD50 of 10(-3) M and promoted by dithiothreitol, while the protease working at pH 8.5 was inhibited by phenylmethylsulfonyl fluoride with LD50 of 10(-5) M and was promoted by ATP (excess ATP beyond 2 mM inhibited the activity reversely). The protease of pH 8.5 had the activity of ATPase which might exert the energy to its action. Therefore the former was referred to as a cysteinyl acid protease and the latter, ATP-dependent neutral serine protease.

MeSH Terms

Adenosine-Triphosphate-metabolism
Chromatography,-Gel
Hydrogen-Ion-Concentration
Mice-
*Cysteine-Proteinases-isolation-and-purification
*Serine-Proteinases-isolation-and-purification
*Toxoplasma-enzymology
Serine-Proteinases
Cysteine-Proteinases
Adenosine-Triphosphate