Tyrosine Experimental Procedure

In this section we provide experimental procedures for the synthesis of various 2-nitrophenyl-containing amino acid derivatives glutamic acid derivative 109 230 (Scheme 28), glycine derivative 112 230 and aspartic acid derivative 114 230 (Scheme 29), Fmoc-protected tyrosine derivative 119 234 (Scheme 30), and glycine derivatives 120 235 and 122 232 (Scheme 31). 

Dye-sensitized photooxidation with visible light to identify residues critically involved in the biological activity of enzymes has been introduced by Weil et al. (425). The procedure is mild and moderately selective for some amino acid side chains in addition to tryptophan, tyrosine, histidine, methionine, cysteine and cystine are also photooxidizable. It has been found possible, by an appropriate choice of dye, to bring about specific modification of a particular residue. There is, however, considerable variation in the effects of different dyes and of particular experimental conditions [see ref. 112, 255, 319, 426) for reviews]. 

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