Development of the Schedule for Multiple Parallel “Difficult” Peptide Synthesis on Pins

Table 1

Peptides synthesized with the help of modifications (A)–(D) (see Section 2) of the standard multiple parallel solid-phase peptide synthesis schedule and MALDI-TOF MS peak lists of their nonpurified preparations.

Peptide number	Amino acid sequence and calculated molecular mass (Da) of the peptide^1	Molecular masses of peptide products, obtained by modifications (A)–(D) of the standard multiple parallel synthesis schedule, and relative intensities of the corresponding ion peaks (HPLC with ESI-MS detection)^2
		(A)	(B)	(C)	(D)
1a	Biotin-SGSG TTKVIGGT-(KP) 1497,8	1497.6	1497.5	1497.4	1497.7; 1396.5 (−T; 17%)
2a	Biotin-SGSGQTRTTGGS-(KP) 1528,7	1528.5	1528.6	1528.4	1528.6; 1427.5 (−T; 20%); 1471.4 (−G; 13%); 1370.2 (−G − T; 7%)
3a	Biotin-SGSGNTKLMGGT-(KP) 1542,8	1542.3	1542.7; 1558.8 (Met(O))	1542.8; 1558.7 (Met(O)); 1441.4 (−T; 15%)	1542.6; 1558.6 (Met(O)); 1485.4 (−G; 10%); 1080.7 (Fmoc-TKLMGT-(KP); 5%)
4a	Biotin-SGSGNNYVTGGA-(KP) 1516,7	1516.3	1516.4	1516.4	1516.5; 1459.7 (−G; 15%)
5a	Biotin-S GSGDTRVVGGQ-(KP) 1552,8	1552.6	1552.6; 1495.5 (−G; 10%)	1552.6; 1495.5 (−G; 17%); 1465.5 (−S; 10%)	1552.7; 1451.5 (−T; 17%); 1495.5 (−G; 15%)

1Linker sequence between the octapeptide fragment of HCV envelope protein and biotin moiety is marked by italics. 𝜀-(Lys-Pro)-Diketopiperazine moiety is shown in brackets.
2The intensity of the target product mass peak is taken as 100% in each case. Mass peaks with intensities not less than 5% of target product mass peak intensities are only listed. Lacking residues are shown as (−𝑋) and in bold in peptide sequences.