Other Reasons for Studying Enzymes

While the main focus of this chapter has been on enzymes as the primary molecular targets of drug action, it is worthwhile noting that the quantitative evaluation of enzyme activity has other important roles in drug discovery and development. 

in addition to the primary target, related enzymes may need to be studied as counterscreens to avoid unwanted side effects due to collateral inhibition of the 

A second area of drug discovery and development in which enzyme reactions play a critical role is in the study of drug metabolism and pharmacokinetics. The elimination of xenobiotics, including drug molecules, from systemic circulation is driven by metabolic transformations that are entirely catalyzed by enzymes. Table 1.2 lists some of the enzyme-catalyzed transformations of xenobiotics that commonly contribute to drug molecule elimination. These biotransformation reactions 

Aromatic hydroxylation Aliphatic hydroxylation AM Iydroxylalion N-, O-, 5-Dealkylation Deamination Sulfoxidation Af-Oxidation Dehalogenation 

Ester hydrolysis Amide hydrolysis Peptide hydrolysis 

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