Dansyl chloride (5-dimethylamino-1 -naphthalenesul- fonyl chloride) reacts with amino groups to give a fluorescent derivative. After a

Question:

Dansyl chloride (5-dimethylamino-1 -naphthalenesul- fonyl chloride) reacts with amino groups to give a fluorescent derivative. After a peptide P with the composition (Arg,Asp,Gly,Leu2,Thr,Val) reacts with dansyl chloride at pH 9, it is hydrolyzed in 6 M aqueous HC1. The derivative shown in the equation given in Fig. P26.43, detected by its fluorescence, is isolated after neutralization, along with the free amino acids Arg, Asp, Gly, Leu, and Thr. What conclusion can be drawn about the structure of the peptide from this result?