Open AccessHuman‐Serum Cholinesterase Subunits and Number of Active Sites of the Major Component
Author(s) -
MUENSCH Helmut,
GOEDDE HeinzWerner,
YOSHIDA Akira
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10972.x
Subject(s) - tetramer , guanidine , enzyme , chemistry , chromatography , sedimentation coefficient , protein subunit , electrophoresis , sedimentation equilibrium , centrifugation , polyacrylamide gel electrophoresis , protein quaternary structure , urea , ultracentrifuge , biochemistry , gene
The major C 4 component of human serum cholinesterase was highly purified by a two‐step procedure involving chromatography on DEAE‐cellulose and preparative disc electrophoresis. The final product was about 8000‐fold purified with a yield of 64%. The subunit structure was determined by 8M urea polyacrylamide disc electrophoresis and by the sedimentation equilibrium centrifugation method in 5M guanidine hydrochloride. It was found that the C 4 enzyme has a tetrameric structure. The subunits are equal in size and charge and a molecular weight comparable to that of the C 1 enzyme from native serum. The major C 4 enzyme and the minor C 1 enzyme were subjected to an ‘active enzyme centrifugation’. It was found that the C 4 enzyme was a tetramer and the C 1 , enzyme was a monomer in the presence of substrate. The number of diisopropylphosphofluoridate‐binding sites was measured from the molar ratio of bound diisopropylphosphate to protein. A value close to two binding sites was found for the C 4 enzyme.