Catalase limiting factor

A.24.1 kcatIKM. Chymotrypsin = 2 x 10" Carbonic anhydrase = 7.5 x 10 Catalase = 3.89 x 10 Penicillinase = 4 x 10 Lysozyme = 8.33 X 10". Diffusion is the most likely limiting factor for Cai bonic anhydrase, Catalase, and Penicillinase because their KciaIKm is on the order of 10 Chymotrypsin and lysozyme are most likely limited by something other than diffusion. 

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In the glucose oxidase system, dissolved oxygen concentration as well as glucose levels will influence dehvery response requiring close control of mass-transfer limitations. For both systems containing a protein component, stabihty factors may limit operational hfetime. This may be particularly severe in the case of glucose oxidase where the reaction product H2O2 will accelerate enzyme denaturation unless it is rapidly removed by diffusion or reaction with a second enzyme (peroxidase or catalase). 

An enzyme electrode is basically a dense package of dialyzer, enzyme reactor, and electrode (detector). Enzymes introduce analytical selectivity due to the specificity of the signal-producing interaction of the enzyme with the analyte. They enhance the equihbrium formation of chemical reactions. For example, splitting of H2O2 is accelerated by a factor of 3 x 10 in the presence of catalase. Turnover numbers can be as fast as 6 X 10 s (carbonic anhydrase) where cat/ m approaches the diffusion limited value of 10 s ... 

Superaxide Dismutase (SOD). Manganese-dependent SOD is a mitochondrial enzyme and is an important factor in limiting oxygen toxicity it is one of the most studied enzymes in human biochemistry. The enzyme catalyzes the breakdown of the superoxide radical OJ to H2O2, which is then removed by catalase and glutathione peroxidase. The half-life of this enzyme in blood serum is longer than that of the cytoplasmic Cu, Zn SOD. 

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