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Thromboxane A2 synthase. Modification during “suicide” inactivation. by D.A. Jones; F.A. Fitzpatrick is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

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Thromboxane synthase is a ferrihemoprotein which undergoes mechanism-based inactivation during catalysis. This "suicide" process may be an important factor for limiting thromboxane A2 biosynthesis in cells. Although the kinetics have been characterized for purified enzyme and platelets, the chemical basis for inactivation has remained unclear. Protein modification or alteration of the heme prosthetic group is each compatible with the irreversible nature of suicide inactivation of thromboxane synthase. We have investigated these two possibilities using enzyme purified to homogeneity. Our data show that the Soret absorbance spectrum of thromboxane synthase is unaltered by additions of prostaglandin endoperoxide H2 which cause enzymatic inactivation. Using a coupled cyclooxygenase/thromboxane synthase system and polyacrylamide gel electrophoresis we have demonstrated that the enzyme retains radiolabel under nondenaturing gel conditions. Label incorporation is reduced by the competitive thromboxane synthase inhibitor U63557, an agent that also protects the enzyme from inactivation. Under denaturing conditions the radiolabel localizes with the released heme prosthetic group. In addition

Who reads Thromboxane A2 synthase. Modification during “suicide” inactivation.?

Author

D.A. Jones; F.A. Fitzpatrick

Publisher

Elsevier BV

Published

1991

Language

EN

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)