Figure 5. Plot of enzyme rates in presence of high-affinity soy trypsin inhibitor. Source: Data from Ref. 14.

TNBS (trinitrobenzenesulfonic acid), the e-amino groups of lysine give a high blank value that may be removed by making the succinyl (19) or TV,TV-dimethyl (20) derivative of the protein. The latter is preferable for trypsinlike proteases.

Small synthetic molecules are also useful for assaying proteases. These give a change in spectrophotometric ab-sorbance as they are hydrolyzed, so a continuous assay with its advantages is possible. Table 1 lists a number of small molecule substrates. Most of these are applicable to serine and/or sulfhydryl proteases, with two exceptions: FAGLA is a substrate for metalloprotease (neutral protease), and Z-Gly-Phe is a carboxypeptidase substrate. Acidic protease may be assayed using a chromogenic peptide. Aminopeptidase is usually assayed using an amino acid derivative such as L-leucine-/?-naphthylamide.

Protease Assays. Most assays with protein substrates involve incubation for a set length of time, stopping the reaction with TCA (trichloroacetic acid), and measuring the amount of soluble peptide. Buffered TCA (0.11 MTCA, 18 g/L; 0.22 M sodium acetate, 18 g/L; and 0.33 M acetic acid, 19.8 g/L) gives superior enzyme linearity compared

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

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