Semicarbazide-sensitive amine oxidase in pig heart.

A semicarbazide-sensitive amine oxidase (SSAO) (E.C.1.4.3.6) has been purified from pig heart. Western blot analysis showed that the enzyme reacts with a polyclonal antibody raised against homogeneous crystalline pig plasma benzylamine oxidase (BAO). A subunit molecular mass of 97 KDa obtained by SDS electrophoresis is identical to the plasma enzyme. The purification procedure consisted of sequential DEAE cellulose, octyl-Sepharose, Con A-Sepharose and hydroxyapatite columns. Two peaks of activity were obtained on octyl-Sepharose which were found to be kinetically and immunologically indistinguishable. The specific activity of the purified enzyme was 0.045 mumol/min/mg of protein at 37 degrees C and the Km for benzylamine was estimated to be 63 microM. The enzyme was inhibited by carbonyl reagents such as semicarbazide but was insensitive to the effect of pargyline.

Purification and properties of low-Km aldehyde reductase from ox brain.

A low-Km aldehyde reductase (alcohol:NADP+ oxidoreductase, EC 1.1.1.2), which may be identical with aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21), has been purified from ox brain to homogeneity. It was shown to be a monomer with Mr values of 31 000 and 35 100 being obtained by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, respectively. The enzyme catalyses the NADPH-dependent reduction of a number of aromatic and sugar aldehydes. The activity of the enzyme with 133 microM NADH was about one-third of that with 120 microM NADPH. Activity with both these coenzymes was optimum at pH 6.2 and was inhibited by increasing the ionic strength with KCl, NaCl or NaNO3. In contrast, the activity was stimulated by sodium phosphate. The activity with NADH as the coenzyme was more sensitive to stimulation by phosphate and to inhibition by increasing ionic strength than that determined with NADPH.