Interaction of divalent metal ions with Zn2+-glycerophosphocholine cholinephosphodiesterase from Ox brain

• Published in: Neurochemical research Vol. 22; no. 12; pp. 1471 - 1476
• Main Authors: KUN JONG LEE, MEE REE KIM, KIM, Y.-B, MYUNG, P.-K, SOK, D.-E
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01.12.1997; Springer Nature B.V
• Subjects: Biochemistry and metabolism; Biological and medical sciences; Central nervous system; Enzymes; Fundamental and applied biological sciences. Psychology; Vertebrates: nervous system and sense organs; Enzyme; Central nervous system; Ox; Molecular interaction; Esterases; Phosphoric diester hydrolases; Anionic site; Vertebrata; Mammalia; Glycerophosphocholine cholinephosphodiesterase; Hydrolases; Catalytic site; Artiodactyla; Divalent metal; Ungulata; Brain (vertebrata)
• ISSN: 0364-3190; 1573-6903
• DOI: 10.1023/A:1021902428146

The effect of divalent metal ions on the activity of glycerophosphocholine cholinephosphodiesterse from ox brain was examined. Zn^sup 2+^- and Co^sup 2+^-glycerophosphocholine cholinephosphodiesterases were prepared from the exposure of apoenzyme to Zn^sup 2+^ and Co^sup 2+^, respectively, and the properties of two metallo-phosphodiesterases were compared to those of native phosphodiesterase. Although two metallo-enzymes were similar in expressing Km value, optimum pH or sensitivity to Cu^sup 2+^, they differed in the susceptibility to the inhibition by thiocholine or tellurite; while Co^sup 2+^-phosphodiesterase was more sensitive to tellurites, Zn^sup 2+^-phosphodiesterase was more susceptible to inhibition by thiocholine. In addition, Zn^sup 2+^-phosphodiesterase was more thermo-stable than Co^sup 2+^ enzyme. Separately, when properties of native phosphodiesterase were compared to those of each metallo-phosphodiesterase, native phosphodiesterase was found to be quite similar to Zn^sup 2+^-phosphodiesterase in many respects. Even in thermo-stability, native enzyme resembled Zn^sup 2+^-phosphodiesterase rather than Co^sup 2+^-enzyme. Consistent with this, the stability of native phosphodiesterase was maintained in the presence of Zn^sup 2+^, but not Co^sup 2+^. Mn^sup 2+^ was also as effective as Zn^sup 2+^ in the stabilization of the enzyme. Noteworthy, the native enzyme was found to be inhibited competitively by Cu^sup 2+^ with a Ki value of 20 μM, and its inhibitory action was antagonized effectively by Zn^sup 2+^ or Co^sup 2+^. Also, choline, another competitive inhibitor of the enzyme, appeared to antagonize the inhibitory action of Cu^sup 2+^. Taken together, it is suggested that there may be multiple binding sites for divalent metal ions in the molecule of glycerophosphocholine cholinephosphodiesterase.[PUBLICATION ABSTRACT]