Application of N–C- or C–N-directed sequential native chemical ligation to the preparation of CXCL14 analogs and their biological evaluation

Efficient one-pot synthesis of CXCL14 and its derivative using an N -sulfanylethylanilide peptide as a peptide thioester equivalent and their biological evaluation

“…The N-terminal fragment 1 and the C-terminal fragment 3 were prepared by Boc and Fmoc-based SPPS according to our previous study. 23 Having prepared the three fragments required for the construction of CXCL14, we attempted the N-to-C-directive one-pot/sequential NCL protocol using the N-terminal cysteinyl SEAlide peptide 2 (Scheme 2, Fig. 2).…”

“…Taking this into account, we previously achieved the chemical synthesis of CXCL14 and its derivative using C-to-N and N-to-C-directive sequential NCL, respectively, where the N-terminal protected thioester (C-to-N) and N-terminal cysteinyl thioacid (N-to-C) were employed as the middle fragment. 23 Previous synthetic strategies involved several experimental manipulations including purification after the first NCL, removal of the N-terminal cysteine protection (C-to-N) and conversion of thioacid to thioester (N-to-C), which resulted in low overall yields. Recently, we discovered that the N-sulfanylethylanilide (SEAlide) peptide efficiently functions as a thioester equivalent in the presence of phosphate salts to participate in NCL [24][25][26] (Scheme 1a).…”

CXCL14 is a natural inhibitor of the CXCL12–CXCR4 signaling axis

“…In brief, 5 × 10 5 cells were suspended in 50 μl RPMI‐1640 containing 0.1% fatty acid‐free BSA and 20 mM HEPES (pH 7.5) and incubated on ice for 2 h with 50 μl 125 I‐labeled CXCL14 in the presence or absence of 3 μM unlabeled CXCL14. For the cold competition of 125 I‐CXCL14, a synthetic CXCL14 analog ( 49 Gly) was used [18]. Cells were centrifuged at 7500× g on a 150 μl oil cushion in a 0.4 ml polyethylene tube.…”

Dimeric peptides of the C‐terminal region of CXCL14 function as CXCL12 inhibitors

“…CXCL14 peptide (77 amino acid residues) was chemically synthesized as previously described [12], and used as full length CXCL14 in this study. CXCL14(1–50)–CXCL12(51–72) chimera and CXCL(Δ29–49) were also synthesized by the procedure essentially similar to that used for the full length CXCL14.…”