Fumarase: [EC 4.2.1.2 l-Malate hydro-lyase]

Author: Hill, Robert L.; Bradshaw, Ralph A.

Description: This chapter discusses the distinct differences in the chemical and physical properties of fumarate and L-malate, allowing fumarase to be assayed in several ways. The most convenient method is a continuous assay, in which changes in fumarate concentration are measured spectrophotometrically between 250 and 300 mu. The activity of fumarase is extremely sensitive to temperature and to the concentration and type of anion in the assay mixture. The purification procedure described is developed from methods described earlier by Massey and by Frieden et al. This method gives a higher yield than the earlier methods, and requires only a short time to obtain pure enzyme. As much as 100 mg of crystalline fumarase may be obtained per kilogram of pig heart muscle, an increase of 5 to 6 times the yield given by the other methods. The low yields given by earlier methods, appear to have resulted from the loss of 60-70% of the fumarase content of heart muscle when the tissue was washed with water prior to extraction of fumarase with buffer. The enzyme shows a bell-shaped dependence on pH, which suggests that fumarase possesses, both an acidic and basic functional group in its active site.

Subject headings: Fumarase; Fumarate; L-malate

Publication year: 1969

Journal or book title: Methods in Enzymology

Volume: 13

Issue:

Pages: 91-99

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Type: Journal Article

Serial number: 2320