User Bulletin No. 18
Peptide Synthesizer
April 28, 1987 (updated 09/2002)
SUBJECT: DEFORMYLATION OF PEPTIDES SYNTHESIZED USING TRP
(CHO) PROTECTION
Author: Alan Culwell and James T. Sparrow
Introduction The formyl (CHO) protecting group of tryptophan is an HF, TFMSA stable species.
Deformylation of a peptide synthesized by using TRP (CHO) requires a separate step
after strong acid cleavage. Since the deformylation of Trp (CHO) can pose problems to
even the experienced peptide chemist, the following procedure should be strictly
followed.
Procedure 1. Dissolve the peptide containing Trp (CHO) in 6M guanidine HC1 to produce a
concentration between 1 and 10 mg/mL.
2. Perform a UV spectral analysis on the dissolved peptide. For a peptide containing
Trp (CHO), the 300 nm absorbance is greater than the 280 nm absorbance, as
shown on Figure 1.
Figure 1. UV spectral analysis of a peptide containing Trp (CHO) before deformylation with
ethanolamine.