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2000 (1)
1Author    KunjanR. Dave, AnshuR. Syal, SurendraS. KatyareRequires cookie*
 Title    Tissue Cholinesterases. A Comparative Study of Their Kinetic Properties  
 Abstract    The substrate saturation and temperature-dependent kinetic properties of soluble and membrane-bound forms of acetylcholinestarase (A C h E) from brain and butyrylcholinester­ ase (B C h E) from heart and liver were examined. In simultaneous studies these parameters were also measured for A C h E in erythrocyte membranes and for B C h E in the serum from rat and humans. For both soluble and membrane-bound forms of the enzyme from the three tissues, two components were discernible. In the brain, K m of component I (high affinity) and component II (low affinity) was somewhat higher in membrane-bound form than that of the soluble form components, while the Vmax values were significantly higher by about five fold. In the heart, K m of component II was lower in membrane-bound form than in the soluble form, while Vmax for both the components was about four to six fold higher in the membrane-bound form. In the liver, Vmax was marginally higher for the two components of the membrane-bound enzyme; the K m only of component I was higher by a factor of 2. In the rat erythrocyte membranes three components of A C h E were present showing increasing values of K m and Vmax. In contrast, in the human erythrocyte membranes only two com po­ nents could be detected; the one corresponding to component II of rat erythrocyte mem­ branes was absent. In the rat serum two components of B C h E were present while the human serum was found to possess three components. Component I of the human serum was missing in the rat serum. Temperature kinetics studies revealed that the Arrhenius plots were bi-phasic for most of the systems except for human serum. Membrane binding of the enzyme resulted in decreased energy of activation with shift in phase transition temperature (r t) to near physiological temperature. 
  Reference    Z. Naturforsch. 55c, 100 (2000); received June 16/August 24 1999 
  Published    2000 
  Keywords    Acetylcholinesterase, Butyrylcholinesterase, Substrate Kinetics, Temperature Kinetics 
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 TEI-XML for    default:Reihe_C/55/ZNC-2000-55c-0100.pdf 
 Identifier    ZNC-2000-55c-0100 
 Volume    55