Tryptophan chemical modification reagents

In lysozyme the reactivity of the six tryptophans to various reagents correlates nicely with their positions observed in the crystal structure. This and many other detailed chemical modification studies on lysozyme are summarised in references 153 and 154. 

With the rapid advancement of microbore and reverse phase technology m HPLC, the escalating popularity of this analytical technique is not unexpected. Generally, in HPLC no cleanup procedure is necessary for biological samples. Some of the ammo acids can be analyzed directly without prior derivatization, as is the case with tyrosine, tryptophan, and their metabolites. However, the use of fluorogenic derivatization reagents is a common practice. The ammo group is the only one that requires chemical modification prior to analysis... 

The reagents that are used most widely for the chemical modification of tryptophan in proteins are limited to simple, readily available... 

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