1,2,4-Triazole

PepSAVI-MS Reveals a Proline-rich Antimicrobial Peptide in Amaranthus tricolor

“…Isobaric stereochemical modifications are difficult to detect using traditional MS approaches, but may be identified chromatographically by comparing the retention times of inactive synthetic and active native peptides. 50,52,53 During strong cation exchange (SCX) fractionation, it was observed that native Atr-AMP1 has a wide elution profile across SCX fractions (SI Figure S9a) which closely mirrors the activity of SCX fractions against E. coli ATCC 25922 (SI Figure S9b). When synthetic Atr-AMP1 (hyP4) was subjected to the same SCX separation conditions, it had a longer retention time than native Atr-AMP1 (SI Figure S9a).…”

“…Stereochemical modifications of the active peptide could change the secondary structure of Atr-AMP1, affecting the strength of its interaction with the anionic stationary phase, thus altering its retention time. For example, the presence of a cis-proline has been shown to decrease SCX retention time and confer activity, 50,53 additionally the presence of 3-hydroxyproline instead of 4-hydroxyproline has been shown to impact reversed-phase retention and here may alter SCX retention and influence activity. 54 The extremely low error (less than 1 ppm) between the calculated and experimental mass of Atr-AMP1 and the thorough validation of the sequence via proteolytic digestion and chemical derivatization suggests that one or more unknown isobaric stereochemical modifications such as cis/trans isomerization may be responsible for the lack of activity and retention time shift observed in the synthetic peptide.…”