CHROMOGENIC SUBSTRATES UNIVERSITY | PROTEOLYTIC MECHANISM
What is a chromogenic Substrate?
Specificity and Selectivity
Substrates in Practice
Protein Concentrations in Plasma
Theoretical Basis for Calculation
International Units and Enzyme Activity
The proteolytic mechanism of serine proteasesThe bond-cleaving reaction exerted by a serine protease on its substrate is the result of an interaction between the substrate and the charge relay network of the enzyme.
Figure 1. Charge realy network of serine proteases.
The proteolytic action of a serine protease on its substrate comprises several steps starting with the formation of a non-covalent complex between the enzyme and the substrate. A nucleophilic attack by the serine hydroxyl group on the amide carbonyl carbon atom in the substrate results in cleavage of the amide bond and the formation of an acyl-enzyme intermediate.
Figure 2. Formation of an acyl-enzyme intermediate.
The acyl-enzyme ester bond is then hydrolysed in the rate limiting step and the enzyme is now free to catalyze the cleavage of another substrate molecule.
Figure 3. Hydrolysis of the acyl-enzyme intermediate.
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