LONG-RANGE INTRAMOLECULAR S- TO N-ACYL TRANSFERS
10 Lovrinovic M, Niemeyer CM. Microtiter plate-based screening for the op-
timization of DNA-protein conjugate synthesis by means of expressed
protein ligation. ChemBioChem: Eur. J. Chem. Biol. 2007; 8: 61–67.
11 Dawson PE, Muir TW, Clark-Lewis I, Kent SBH. Synthesis of proteins by
native chemical ligation. Science 1994; 266: 776–779.
12 Kent SBH. Total chemical synthesis of proteins. Chem. Soc. Rev. 2009;
38: 338–351.
13 Camarero JA, Fushman D, Cowburn D, Muir TW. Peptide chemical liga-
tion inside living cells: in vivo generation of a circular protein domain.
Bioorg. Med. Chem. 2001; 9: 2479–2484.
Conclusions
Stable, amino-unprotected S-acyl-monoisotri- and S-acyl-monoisotetra-
cysteine-peptides containing a-, b- and/or g-amino acid residues un-
dergo chemical ligations in which the cysteine S-acyl groups migrate
to the N-terminal amino acids via 9, 10-, 12-, and 13-membered cyclic
transition states to form the corresponding native tripeptide and tet-
rapeptide analogs. We have already demonstrated [32] by quantum
chemical calculations that cross-transition state H-bonding and tran-
sition state size can favor or disfavor the intramolecular reaction.
Now, we see that not only hydrogen bonding but also NH–p interac-
tions can affect regioselectivity of the S! N-acyl transfers. The
present work describing a range of novel long-range S- to N-acyl
migrations offers evidence that relates to the challenging problem
of successfully coupling large peptides and peptide analog fragments.
Work is currently in progress on conformational studies of various
transition states of size 6–20 to further understand such interactions.
14 Giriat I, Muir TW. Protein semi-synthesis in living cells. J. Am. Chem.
Soc. 2003; 25: 7180–7181.
15 Lockless SW, Muir TW. Traceless protein splicing utilizing evolved split
inteins. Proc. Natl. Acad. Sci. USA 2009; 106: 10999–11004.
16 Offer J, Boddy CNC, Dawson PE. Extending synthetic access to
proteins with a removable acyl transfer auxiliary. J. Am. Chem. Soc.
2002; 124: 4642–4646.
17 Lutsky MY, Nepomniaschiy N, Brik A. Peptide ligation via side-chain
auxiliary. Chem. Commun. 2008; 10: 1229–1231.
18 Haase C, Seitz O. Internal cysteine accelerates thioester-based peptide
ligation. Eur. J. Org. Chem. 2009; 13: 2096–2101.
19 Marinzi C, Bark SJ, Offer J, Dawson PE. A new scaffold for amide ligation.
Bioorg. Med. Chem. 2001; 9: 2323–2328.
20 Kemp DS, Galaktos NG. Peptide-synthesis by prior thiol capture. A
convenient synthesis of 4-hydroxy-6-mercaptodibenzofuran and
novel solid-phase synthesis of peptide-derived 4-(acyloxy)-6-mercap-
todibenzofurans. J. Org. Chem. 1986; 51: 1821–1829.
21 Kemp DS, Galaktos NG, Bowen B, Tan K. Peptide synthesis by prior
thiol capture. Design of templates for intramolecular O,N-acyl transfer
4,6-disubstituted dibenzofurans as optimal spacing elements. J. Org.
Chem. 1986; 51: 1829–1838.
22 Kemp DS, Galaktos NG, Dranginis S, Ashton C, Fotouhi N, Curran T.
Peptide synthesis by prior thiol capture. Amide bond formation:
the effect of a side-chain substituent on the rates of intramolecular
O,N-acyl transfer. J. Org. Chem. 1986; 51: 3320–3324.
23 Kemp DS, Carey RI. Boc-L-Dmt-OH as a fully N,S-blocked cysteine for pep-
tide synthesis by prior thiol capture. Facile conversion of N-terminal Boc-L-
Dmt-peptides to H-Cys(Scm)-peptides. J. Org. Chem. 1989; 54: 3640–3646.
24 Kemp DS, Carey RI. Synthesis of a 39-peptide and a 25-peptide by thiol
capture ligations: observation of a 40-fold rate acceleration of the intra-
molecular O,N-acyl-transfer reaction between peptide fragments bear-
ing only cysteine protective groups. J. Org. Chem. 1993; 58: 2216–2222.
25 Bennett CS, Dean SM, Payne RJ, Ficht S, Brik A, Wong C-H. Sugar-
assisted glycopeptide ligation with complex oligosaccharides: scope
and limitations. J. Am. Chem. Soc. 2008; 130: 11945–11952.
26 Katritzky AR, Abo-Dya NE, Tala SR, Abdel-Samii ZK. The chemical
ligation of selectively S-acylated cysteine peptides to form native pep-
tides via 5-, 11- and 14-membered cyclic transition states. Org. Biomol.
Chem. 2010; 8: 2316–2319.
Experimental
General Methods
Details of the syntheses and transformations with related analytical
data are reported in the Supplementary Information. Melting
points were determined on a capillary point apparatus equipped
with a digital thermometer. NMR spectra were recorded in CDCl3,
1
DMSO-d6 or CD3OD-d4 operating at 300 MHz for H and 75 MHz
for 13C with TMS as an internal standard. All microwave-assisted
reactions were carried out with a single mode cavity CEM Discover
microwave synthesizer. The reaction mixtures were transferred into
a 10-ml glass pressure microwave tube equipped with a magnetic
stirrer bar. The tube was closed with a silicon septum, and the
reaction mixture was subjected to microwave irradiation (Discover
mode; run time: 60 s; PowerMax-cooling mode).
Acknowledgements
We thank the University of Florida, the Kenan Foundation, and
King Abdulaziz University, Jeddah, Saudi Arabia for financial sup-
port. We thank Dr C. D. Hall and Dr E. Todadze for helpful discus-
sions and Dr J Johnson for help in HPLC-MS analyses.
27 Katritzky AR, Tala SR, Abo-Dya NE, Ibrahim TS, El-Feky SA, Gyanda K,
Pandya KM. Chemical ligation of S-acylated cysteine peptides to form
native peptides via 5-, 11-, and 14-membered cyclic transition states.
J. Org. Chem. 2011; 76: 85–96.
28 Katritzky AR, Angrish P, Todadze E. Chiral acylation with N-(protected
a-aminoacyl)benzotriazoles for advantageous syntheses of peptides
and peptide conjugates. Synlett 2009; 15: 2392–2411.
29 Hansen FK, Ha K, Todadze E, Lillicotch A, Frey A, Katritzky AR. Microwave-
assisted chemical ligation of S-acyl peptides containing non-terminal
cysteine residues. Org. Biomol. Chem. 2011; 20: 7162–7167.
30 Nam N, Kim Y, You Y, Hong D, Kimb H, Ahn B. Water soluble pro-
drugs of the antitumor agent 3-[(3-amino-4-methoxy)phenyl]-2-
(3,4,5-trimethoxyphenyl) cyclopent-2-ene-1-one. Bioorg. Med. Chem.
2003; 11: 1021–1029.
References
1 Hackenberger CPR, Schwarzer D. Chemoselective ligation and modifi-
cation strategies for peptides and proteins. Angew. Chem. Int. Ed.
2008; 47: 10030–10074.
2 Kang J, Macmillan D. Peptide and protein thioester synthesis via N!S
acyl transfer. Org. Biomol. Chem. 2010; 8: 1993–2002.
3 Mende F, Seitz O. 9-Fluorenylmethoxycarbonyl-based solid-phase synthe-
sis of peptide a-thioesters. Angew. Chem. Int. Ed. 2011; 50: 1232–1240.
4 Wang P, Miranda LP. Fmoc-protein synthesis: preparation of peptide
thioesters using a side-chain anchoring strategy. Int. J. Pept. Res. Ther.
2005; 11: 117–123.
5 Dawson PE, Kent SBH. Synthesis of native proteins by chemical ligation.
31 Ha K, Chahar M, Monbaliu MJ-C, Todadze E, Hansen FK, Oliferenko AA,
Ocampo CE, Leino D, Lillicotch A, Stevens CV, Katritzky AR. Long-
range intramolecular S!N acyl migration: a study of the formation
of native peptide analogues via 13-, 15-, and 16-membered cyclic
transition states. J. Org. Chem. 2012; 77: 2637–2648.
Annu. Rev. Biochem. 2000; 69: 923–960.
6 Camarero JA, Shekhtman A, Campbell EA, Chlenov M, Gruber TM,
Bryant DA, Darst SA, Cowburn D, Muir TW. Autoregulation of a bacte-
rial s factor explored by using segmental isotopic labeling and NMR.
Proc. Natl. Acad. Sci. USA 2002; 99: 8536–8541.
32 Oliferenko AA, Katritzky AR. Alternating chemical ligation reactivity of
S-acyl peptides explained with theory and computations. Org. Biomol.
Chem. 2011; 9: 4756–4759.
34 Ottiger P, Pfaffen C, Leist R, Leutwyler S, Bachorz RA, Klopper W. Strong N-
H...p hydrogen bonding in amide-benzene interactions. J. Phys. Chem. B
2009 113: 2937–2943.
7 Cowburn D, Muir TW. Segmental isotopic labeling using expressed
protein ligation. Methods Enzymol. 2001; 339: 41–54.
8 Dose C, Seitz O. Convergent synthesis of peptide nucleic acids by native
chemical ligation. Org. Lett. 2005; 7: 4365–4368.
9 Ficht S, Dose C, Seitz O. As fast and selective as enzymatic ligations:
unpaired nucleobases increase the selectivity of DNA-controlled native
chemical PNA ligation. ChemBioChem: Eur. J. Chem. Biol. 2005; 6: 2098–103.
J. Pept. Sci. 2012; 18: 704–709 Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/jpepsci