An Effective Method of On-Resin Disulfide Bond Formation in Peptides

Galande, Amit K.; Weissleder, Ralph; Tung, Ching–Hsuan

doi:10.1021/cc049839r

Cited by 42 publications

(37 citation statements)

References 25 publications

(26 reference statements)

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“…The method presented here is related HARRIS, FLEMER AND HONDAL to the work presented earlier by Galande et al who reported on a new method for making disulfide bonds on-resin [17]. We have found that one reagent used by Galande et al, 2,2 -dithiobis(5-nitropyridine) (DTNP), could be used directly to deprotect Sec(Mob) residues, and with the addition of thioanisole, Cys(Mob) and Cys(Acm) residues could also be deprotected.…”

Section: Introductionmentioning

confidence: 75%

“…In order to activate the sulfhydryl side-chain of Cys for cyclization, we used a procedure developed by Galande et al for onresin formation of 5-Npys-protected sulfhydryls [17]. After conversion of the Cys(StBu) derivative to a Cys(5-Npys) derivative, simultaneous cyclization/deprotection to form a selenylsulfide bond was then initiated by incubating the resin with 1% TFA in DCM, followed by the addition of neat TFA/scavenger cocktails as described in Table 1.…”

Section: Formation Of 5-npys-protected Cysteine Residues On-resin Andmentioning

confidence: 99%

“…Inspired by a recent report by Galande et al [17] who developed a new method for making disulfide bonds on-resin using 5-Npys-activated Cys residues, we then attempted to drive the cyclization reaction of the tripeptide to completion by using a 5-Npys-activated Cys residue in the adjacent position. We reasoned that the disulfide bond of a Cys(5-Npys) residue in the neighboring position to Sec(Mob) should be a much better electrophile and thus improve the cyclization.…”

Section: Model Cyclization Reaction Involving Sec(mob) and Cys(mob)mentioning

confidence: 99%

“…We reasoned that the disulfide bond of a Cys(5-Npys) residue in the neighboring position to Sec(Mob) should be a much better electrophile and thus improve the cyclization. We used the procedure developed in [17] to convert a Cys(StBu) residue to a Cys(5-Npys) residue on-resin so that our peptide was of the sequence Cys(5-Npys)-Sec(Mob)-Gly-PAL-Resin.…”

Section: Model Cyclization Reaction Involving Sec(mob) and Cys(mob)mentioning

confidence: 99%

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Studies on deprotection of cysteine and selenocysteine side‐chain protecting groups

Harris¹,

Flemer²,

Hondal³

2006

Journal of Peptide Science

101

113

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Abstract:We present here a simple method for deprotecting p-methoxybenzyl groups and acetamidomethyl groups from the sidechains of cysteine and selenocysteine. This method uses the highly elecrophilic, aromatic disulfides 2,2 -dithiobis(5-nitropyridine) (DTNP) and 2,2 -dithiodipyridine (DTP) dissolved in TFA to effect removal of these heretofore difficult-to-remove protecting groups. The dissolution of these reagents in TFA, in fact, serves to 'activate' them for the deprotection reaction because protonation of the nitrogen atom of the pyridine ring makes the disulfide bond more electrophilic. Thus, these reagents can be added to any standard cleavage cocktail used in peptide synthesis.The p-methoxybenzyl group of selenocysteine is easily removed by DTNP. Only sub-stoichiometric amounts of DTNP are required to cause full removal of the p-methoxybenzyl group, with as little as 0.2 equivalents necessary to effect 70% removal of the protecting group. In order to remove the p-methoxybenzyl group from cysteine, 2 equivalents of DTNP and the addition of thioanisole was required to effect removal. Thioanisole was absolutely required for the reaction in the case of the sulfur-containing amino acids, while it was not required for selenocysteine. The results were consistent with thioanisole acting as a catalyst. The acetamidomethyl group of cysteine could also be removed using DTNP, but required the addition of >15 equivalents to be effective. DTP was less robust as a deprotection reagent. We also demonstrate that this chemistry can be used in a simultaneous cyclization/deprotection reaction between selenocysteine and cysteine residues protected by p-methoxybenzyl groups to form a selenylsulfide bond, demonstrating future high utility of the deprotection method.

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Section: Introductionmentioning

confidence: 75%

Section: Formation Of 5-npys-protected Cysteine Residues On-resin Andmentioning

confidence: 99%

Section: Model Cyclization Reaction Involving Sec(mob) and Cys(mob)mentioning

confidence: 99%

Section: Model Cyclization Reaction Involving Sec(mob) and Cys(mob)mentioning

confidence: 99%

See 2 more Smart Citations

Studies on deprotection of cysteine and selenocysteine side‐chain protecting groups

Harris¹,

Flemer²,

Hondal³

2006

Journal of Peptide Science

101

113

View full text Add to dashboard Cite

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“…The resulting free thiol of CysA11 quickly reacted with CysA6-SNPy in CH 2 Cl 2 to form the disulfide A6-A11 to provide 8. [9] Peptide cleavage from 8 was conducted with a cocktail of TFA, TIS, and H 2 O, and the resulting 5 was found to be easily solubilized in 0.05 % TFA-containing aqueous acetonitrile and readily purified by C18 RP-HPLC with an overall yield of 35 % based on the substitution of the starting Rink amide resin (Table 1 and Figure S1). Interestingly, it was noted that the tert-butylthiol group on CysA6 of the resin-bound all-amide backbone A chain S17, having the same side-chain protection scheme as that for 6, was completely inert to the treatment of 25 % bmercaptoethanol in DMF (see Figure S4 in the Supporting Information), presumably because of the aggregation of S17 which prohibited access of the reagents to CysA6.…”

mentioning

confidence: 99%

A Synthetic Route to Human Insulin Using Isoacyl Peptides

et al. 2014

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The chemical synthesis of insulin has been a longstanding challenge, mainly because of the notorious hydrophobicity of the A chain and the complicated topology of this 51-mer peptide hormone consisting of two chains and three disulfide bonds. Reported herein is a new synthetic route utilizing the isoacyl peptide approach to address the hydrophobicity problems. The incorporation of isoacyl dipeptide segments into both A and B chains greatly improved their preparation and purification, and the RP-HPLC recovery of the chain ligation intermediates. The new route affords human insulin with a yield of 68 % based on the starting purified A chain and an overall yield of 24 % based on the substitution of the resin used for the preparation of A chain. To the best of our knowledge, this represents the most efficient route of human insulin chemical synthesis reported to date.

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