Fig. 4. Peptide modification with Petasis reaction. Peptides with sequence XAF, where X represents a variable amino acid were screened for Petasis reaction with PMB 3b and a variety of aldehydes 2b, 2d and water-soluble SAL analogue 2a′. % conversion to Petasis products were determined by LC/MS. Reaction conditions: XAF (12–17 mM), RCHO 2 (1.5 equiv. 18–25.5 mM), PMB 3b (8 equiv. 96–136 mM) in 25 mM buffer (pH 7.3) : DMSO (4 : 1) and 37 °C. The samples were incubated for 4 h.
