1-Hydroxy-7-azabenzotriazole. An efficient peptide coupling additive

Carpino, Louis A.

doi:10.1021/ja00063a082

Cited by 1,449 publications

(1,003 citation statements)

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“…In particular, couplings involving the severely sterically hindered (aMe)Pro residue were achieved by C-activation with N-ethyl, N 0 -[3-(dimethylamino)-propyl] carbodiimide and as additive either 1-hydroxy-1,2,3-benzotriazole 33 or 7-aza-1-hydroxy-1,2,3-benzotriazole. 34 Yields were from good to excellent, with the single exception of that of the Aib-D-(aMe)Pro bond (24%). 35 Details of syntheses and chemical characterizations will be reported elsewhere.…”

Section: Methodsmentioning

confidence: 99%

C^α‐Methyl proline: A unique example of split personality

et al. 2007

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Methylation at the Cα‐position of a Pro residue was expected to lock the preceding tertiary amide (ω) torsion angle of the resulting (αMe)Pro to the trans disposition and to restrict the ϕ,ψ surface to the single region where the 310/α‐helices are found (in this five‐membered ring residue ϕ is severely constrained to about ±65° by its cyclic nature). The results of the present X‐ray diffraction work on a selected set of four Nα‐blocked, (αMe)Pro‐containing, dipeptide N′‐alkylamides clearly show that, although the region of the conformational map largely preferred by (αMe)Pro would indeed be that typical of 310/α‐helices, the semi‐extended [type‐II poly(Pro)n helix] region can also be explored by this extremely sterically demanding Cα‐tetrasubstituted α‐amino acid. In addition, the known high propensity for β‐turn formation of the Pro residue is further enhanced in peptides based on its Cα‐methylated derivative. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 465–470, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

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Section: Methodsmentioning

confidence: 99%

C^α‐Methyl proline: A unique example of split personality

et al. 2007

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“…21 Details of their characterization are reported in the ESI. † Spectroscopy grade solvents (Carlo Erba, Milan, Italy) were used for all experiments.…”

Section: Methodsmentioning

confidence: 99%

A single-residue substitution inhibits fibrillization of Ala-based pentapeptides. A spectroscopic and molecular dynamics investigation

et al. 2014

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The aggregation properties of two Ala-based pentapeptides were investigated by spectroscopic techniques and molecular dynamics (MD) simulations. The two peptides, both functionalized at the N-terminus with a pyrenyl group, differ in the insertion of an a-aminoisobutyric acid residue at position 4. We showed that this single modification of the homo-peptide sequence inhibits the aggregation of the pentapeptide in aqueous solutions. Atomic force microscopy imaging revealed that the two peptides form mesoscopic aggregates of very different morphologies when deposited on mica. MD experiments showed that the two peptides have a very different propensity to form b-pleated sheet structures, as confirmed by our spectroscopic measurements. The implications of these findings for our understanding of the mechanism leading to the formation of amyloid structures, primary responsible for numerous neurodegenerative diseases, are also discussed.

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“…The DCC/HOBT/CuCl 2 method 29,39 failed in this instance. Eventually, we found that Carpino's excellent HATU reagent 50 accomplished this cyclisation in 25% overall yield over two steps, provided high-dilution conditions and a large excess of HATU 50 were employed.…”

Section: Jonathanmentioning

confidence: 99%

“…Although (+)-azinothricin was itself never tested as an antitumour drug, it was documented as being one of the most potent Gram-positive antibiotics ever discovered, its MIC values ranging from 0.001-0.016 mg mL À1 against 51 different bacterial strains. Even so, because of a fairly poor toxicological profile in mice (LD 50 = 10 mg kg À1 [intravenous] and 3.2 mg kg À1 [intraperitoneally]), (+)-azinothricin was never taken forward as a new antibiotic drug and, as a result, it initially looked set to rapidly fall from scientific view.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, this was a view that only got further reinforced as later biological test data emerged on the sister molecules (À)-verucopeptin 4 and (+)-GE3. 5 With regards to (À)-verucopeptin, 4 it showed pronounced broad-spectrum antitumour effects in vitro (IC 50 = 0.004 mg mL À1 vs. B16 melanoma; IC 50 = 0.08 mg mL À1 vs. P388 lymphocytic leukaemia), including against a HCT-116 human colon carcinoma cell line (IC 50 = 0.04 mg mL À1 ). However, subsequent in vivo assaying did later reveal that it was a quite specific and selective agent in its therapeutic window.…”

Section: Introductionmentioning

confidence: 99%

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