title: A study of the catalase monomer produced by lyophilization.
abstract: Lyophilization of Dounce and Mourtzikos beef liver catalase (Prep. Biochem. 11 (1981) 501-523) under specified conditions produced conformationally altered but not completely denatured catalase monomer which retained both significant catalatic activity and peroxidatic activity towards ethanol. The same lyophilization procedure used with Sigma Co. catalase produced a mixture of conformationally altered catalase monomer and conformationally altered tetramer which showed still higher catalatic and peroxidatic activities; this was attributed to the presence of the altered tetramer. The catalase monomer obtained by the use of Dounce and Mourtzikos catalase is completely reducible by dithionite, as shown by the two-banded spectrum of the reduced material, but apparently retains enough of its native conformation to show some enzymatic activity, since the fully denatured monomer shows no catalatic or peroxidatic activity towards ethanol. The conformationally altered catalase tetramer, which shows more enzymatic activity than the monomer, evidently retains a higher proportion of its native conformation than the monomer, but still appears to be fully reducible with dithionite. Horseradish peroxidase after reduction with dithionite shows spectral bands at positions close to those of reduced lyophilized catalase, but the relative band heights and contours are different. A possible explanation for the observed differences in lyophilization products depending on the starting material (Sigma Co. catalase versus catalase of Dounce and Mourtzikos) is presented.
mesh_terms: D000818:Animals; D002374:Catalase / Q000302:isolation & purification; D002384:Catalysis; D002417:Cattle; D000431:Ethanol / Q000378:metabolism; D005612:Freeze Drying; D008099:Liver / Q000201:enzymology; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011489:Protein Denaturation; D014461:Ultracentrifugation
chemical_list: D000431:Ethanol; D002374:Catalase