S- aminoethyl- l -cysteine transaminase from bovine brain: purification to homogeneity and assay of activity in different regions of the brain.
A transminase acting on cystathionine, S-aminoethylcysteine and glutamine has been purified to homogeneity from bovine brain by ammonium sulfate precipitation. DE-52 chromatography, octyl-Sepharose chromatography, hydroxylapatite chromatography and gel filtration. The enzyme was purified 4700 times over the bovine brain homogenate and the overall recovery of the enzyme activity was about 18%. As demonstrated by polyacrylamide gel electrophoresis under native or denaturing conditions, the enzyme has a molecular mass of 100 kDa and is composed of two subunits with approximately identical weight. A single active peak was obtained at pH = 5.24 by chromatofocusing of a homogeneous enzyme preparation. K(m) values for S-aminoethylcysteine have been calculated using various ?-keto acids as amino acceptor and K(m) for glutamine has been determined with ?-keto-?-methiolbutyric acid as cosubstrate. The occurrence of the enzyme activity in some bovine brain regions was also studied.
Pensa
B
B
Department of Biochemical Sciences, University of Rome "La Sapienza" and Centro di Biologia Molecolare del Consiglio Nazionale delle Ricerche, Rome, Italy.
Achilli
M
M
Fontana
M
M
Caccuri
A M
AM
Cavallini
D
D