| Abstract: | Incorporation of an unnatural amino acid containing a photolabile group in the side chain allows specific interactions between two proteins to be prevented. The photocaged ras protein in which Asp 38 has been substituted by its β-nitrobenzyl ester (Nb) is unable to interact with its effector protein p120–GAP (see drawing below) although it has the same intrinsic GTPase activity. After photocleavage of the Nb group, 50% of the p120–GAP-dependent GTPase activity relative to the wild-type protein is restored. |
