Peptide o‐Aminoanilides as Crypto‐Thioesters for Protein Chemical Synthesis

Abstract

Fully unprotected peptide o-aminoanilides can be efficiently activated by NaNO2 in aqueous solution to furnish peptide thioesters for use in native chemical ligation. This finding enables the convergent synthesis of proteins from readily synthesizable peptide o-aminoanilides as a new type of crypto-thioesters. The practicality of this approach is shown by the synthesis of histone H2B from five peptide segments. Purification or solubilization tags, which are sometimes needed to improve the efficiency of protein chemical synthesis, can be incorporated into the o-aminoanilide moiety, as demonstrated in the preparation of the cyclic protein lactocyclicin Q.

An explorative study towards the chemical synthesis of the immunoglobulin G1 Fc CH3 domain

“…However, the conversion was incomplete, probably due to the sterically hindered C‐terminal Thr(tBu)‐370. Thus, we decided to cleave the peptide from the resin in the Dbz form 3a , which is more stable than the Nbz form 3 but may be orthogonally converted into a benzotriazole moiety with NaNO 2 and then displaced by the thiol additive in the ligation buffer to afford the peptide thioester in situ . The TFA‐cleaved product 3a showed satisfactory homogeneity (~60%) (Scheme ).…”

“…Unfortunately, in our case, the use of DMF did not solve the problem, and no Nbz peptide was formed (probably, because of the presence of the β‐branched threonine). Thus, we activated the Dbz peptide 3a by converting it into an N‐acyl‐benzotriazole peptide by using NaNO 2 at pH~3, as previously shown by Liu and coworkers . For the Acm cleavage from the C‐terminal free acid of 8 , we used the Pd‐catalyzed reaction reported by Brik and coworkers .…”

Chemical and semisynthesis of modified histones

“…The o ‐aminoanilides were activated to thioesters by using NaNO 2 on the fully deprotected peptides. Subsequent NCL and desulfurization afforded the unmodified H2B .…”

Chemical Synthesis of Phosphorylated Histone H2A at Tyr57 Reveals Insight into the Inhibition Mode of the SAGA Deubiquitinating Module

“…On the other hand, a total chemical synthesis approach, whereby the entire modified protein is synthesized via the assembly of synthetic peptides generated by solid phase peptide synthesis (SPPS), makes it possible to incorporate unlimited variations in the protein sequence, including the installation of PTMs at any desired position(s). [15] …”

“…Notably, despite the presence of methoxylamine, in the second ligation only a minor amount of the side product generated from the attack of methoxylamine on fragment 3 was observed. [15a, 15b, 21] This is probably due to the rapid ligation reaction between fragments 3 and 4 . Subsequently, one-pot desulfurization [22] was carried out in presence of the initiator 2,2′-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (VA-044), TCEP and t -BuSH for 3h to produce the full length histone H2AY57p in ~25% isolated yield (Figure 1).…”