Amine blocking groups acid sensitive

A succinylated casein derivative that has nearly all its amines blocked can be used as a substrate in protease assays (Hatakeyama etal., 1992). As the casein is degraded by a protease, free amines are created from a-chain cleavage and release of a-amino groups. The creation of amines can be monitored by an amine detection reagent such as trinitrobenzene sulfonic acid (TNBS Section 4.3). The procedure forms the basis for a highly sensitive assay for protease activity. 

Blocking of amine groups on proteins also has been used to create a sensitive reagent for measuring protease activity (Hatakeyama etal., 1992). With nearly all the primary amines of casein blocked, an amine detection reagent such as trinitrobenzene sulfonic acid (TNBS) will only minimally react with the protein and form its typical orange derivative. As proteases cleave the protein, however, primary a-amines are created from cleavage of the a-chain peptide bonds, and TNBS can react with them. The more protease activity present, the more color is formed. 

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