Folded and extended structures of homooligopeptides from .alpha.,.alpha.-dialkylated .alpha.-amino acids. An infrared absorption and proton nuclear magnetic resonance study

Bonora, Gian Maria; Toniolo, Claudio; Blasio, Benedetto Di; Pavone, Vincenzo; Pedone, Carlo; Benedetti, Ettore; Lingham, Ian N.; Hardy, P. M.

doi:10.1021/ja00338a025

Cited by 69 publications

(38 citation statements)

References 3 publications

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“…An analysis of the spectrum as a function of concentration (Figure 2) shows that a dilution from 0.75 X to 0.6 X loW3 M produces a significant variation (to higher (14) 1194 (14) 2644 (13) 1784 (8) 3798 (10) 4059 (11) 3680 (14) 5442 (11) 3349 (10) 2998 (7) 3254 (9) 2659 (13) 3436 (13) 2472 (14) 1380 (11) 918 (7) 768 (9) -457 (16) -1401 (13) -742 (14) -482 (13) -1454 (8) 578 (10) 683 (14) 235 (17) 2064 (14) 51 (16) -450 (8) 33 (10) -536 (11) 1225 i7j 1540 (11) 1586 (13) 1238 (10) 935 (9) 878 (12) 1275 (13) 1204 (7) 1393 (8) 1343 (9) 1549 (9) 1958 (9) 1801 (6) 2707 (8) 3390 (10) 3838 (11) 4024 (10) 3087 (8) 3490 (6) 2446 (8) 2019 (14) 2709 (12) 1274 (13) 1833 (10) 1777 (8) 1730 (9) 1546 (12) 734 (10) 1766 (14) 2223 (11) 2007 (6) 3006 (8) 3662 (8) 410 …”

Section: Resultsmentioning

confidence: 99%

A long, regular polypeptide 310-helix

Toniolo¹,

Bonora²,

Bavoso³

et al. 1986

Macromolecules

104

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Nemoto, N.; Landry, M. R.; Noh, I.; Kitano, T.; Wesson, J. A.; Yu, H. Macromolecules 1985,18, 308. Amis, E. J.; Han, C. C.; Matsushita, Y. Polymer 1984,25,650. Van Krevelen, D. W. "Properties of Polymers", 2nd ed.; Elsevier: Amsterdam, 1976; p 339. Smith, B. A.; Samulski, E. T.; Yu, L.-P.; Winnik, M. A., Macromolecules, in press. Smith, B. A.; Samulski, E. T.; Yu, L.-P.; Winnik, M. A. Phys. ABSTRACT The infrared absorption and ' H nuclear magnetic resonance analyses of chloroform solutions of the terminally blocked homooctapeptide from the C,+-dimethylated a-aminoisobutyric acid residue are consistent with the presence of a 310-helical structure of high thermal stability. The crystal structure of the octapeptide, obtained by X-ray diffraction, indicates the formation of a 310-helix, stabilized by six consecutive intramolecular N-H-O=C H bonds of the Clo-I11 (or 111' ) type. This represents the first observation a t atomic resolution of a regular 310-helix larger than two complete tums. Packing of the octapeptide molecules gives rise to a channel in which the solvent (methanol and water) molecules are accommodated.p-BrBz-Aib-0-t -Bu. This compound was synthesized from p-BrBz-Aib-OH and isobutene in anhydrous methylene chloride in the presence of a catalytic amount of H2S04:@ yield 61%; mp 144-145 "C (from ethyl acetate-petroleum ether); R, 0.90, R,

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Section: Resultsmentioning

confidence: 99%

A long, regular polypeptide 310-helix

Toniolo¹,

Bonora²,

Bavoso³

et al. 1986

Macromolecules

104

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“…We and others have already shown by energy calculations that C "-"-dirnethylglycine (or a-aminoisobutyric acid; Aib) strongly stabilizes structures near the 3,,/a-helical region of the confonnational map ('p = +GOO, +200; 4 = +3oo, +200).1.3-7 B y contrast, we have found that peptides from C ". "-di-n-propylglycine (Dpg) prefer the fully extended C, structure ('p = 180°, ic, = 180°).6-8 Solution and crystal-state studies of a number of and Dpg8,'9*20 peptides are in excellent agreement with the theo~i b 2 - 5,[9][10][11][12][13][14][15][16][17][18][19] Biopolymers, Vol. 27, 357-371 (1988 n(H,C) (CH,)n n = l Deg -NH-C-COn = 2 DPg…”

Section: Introductionmentioning

confidence: 94%

Structural versatility of peptides from C^α,α‐dialkylated glycines. I. A conformational energy computation and x‐ray diffraction study of homo‐peptides from C^α,α‐diethylglycine

et al. 1988

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Conformational energy computations on a derivative and a homo‐dipeptide of Cα,α‐diethylglycine were performed. In both cases the N‐ and C‐terminal groups are blocked as acetamido and methylamido moieties, respectively. It was found that the Cα,α‐diethylglycine residues are conformationally restricted and that the minimum energy conformation corresponds to the fully extended C5 structure when the NCαC′ bond angle is smaller than 108° (as experimentally observed). The results of the theoretical analysis are in agreement with the crystal‐state structural propensity of the complete series of N‐trifluoroacetylated homo‐peptides of this Cα,α‐dialkylated residue from monomer to pentamer, determined by x‐ray diffraction and also described in this work. Interestingly, for the first time, a crystallographically planar peptide backbone was observed (in the protected tripeptide). A comparison with peptides of Cα,α‐dimethylglycine, Cα‐methyl, Cα‐ethylglycine, and Cα,α‐di‐n‐propylglycine indicates that the fully extended conformation becomes more stable than the helical structures when both amino acid side‐chain Cβ atoms are substituted.

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“…86,87 However, many recent crystal structure determinations of Dpg and Dbg containing peptides have yielded helical conformations. In short heteromeric sequences, both folded and extended Dpg conformations have been characterized.…”

Section: ±85mentioning

confidence: 99%

Stereochemical Control of Peptide Folding

Kaul

Balaram

1999

Bioorganic & Medicinal Chemistry

153

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AbstractÐStereochemically constrained amino acid residues that strongly favour speci®c backbone conformations may be used to nucleate and stabilize speci®c secondary structures in designed peptides. An overview of the use of aa-dialkyl amino acids in stabilizing helical structures in synthetic peptides is presented, with an emphasis on work carried out in the authors laboratory. a-Aminoisobutyric acid (Aib) and related achiral homologs facilitate stable helix formation in oligopeptides as exempli®ed by a large number of crystal structure determinations in the solid state. The ability to design conformationally rigid helical modules has been exploited in attempts to design structurally well characterized helix-linker±helix, using potential nonhelical linking segments. bHairpin design has been approached by exploiting the tendency of`prime turns' to nucleate hairpin formation. The use of nucleating D Pro-Gly segments has resulted in the generation of several well characterized b-hairpin structures, including the crystallographic observation of b-hairpin in a synthetic apolar octapeptide. Extensions of this approach to three stranded b-sheets and larger structures containing multiple D Pro-Gly segments appear readily possible.

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Folded and extended structures of homooligopeptides from .alpha.,.alpha.-dialkylated .alpha.-amino acids. An infrared absorption and proton nuclear magnetic resonance study

Cited by 69 publications

References 3 publications

A long, regular polypeptide 310-helix

A long, regular polypeptide 310-helix

Structural versatility of peptides from C^α,α‐dialkylated glycines. I. A conformational energy computation and x‐ray diffraction study of homo‐peptides from C^α,α‐diethylglycine

Stereochemical Control of Peptide Folding

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Folded and extended structures of homooligopeptides from .alpha.,.alpha.-dialkylated .alpha.-amino acids. An infrared absorption and proton nuclear magnetic resonance study

Cited by 69 publications

References 3 publications

A long, regular polypeptide 310-helix

A long, regular polypeptide 310-helix

Structural versatility of peptides from Cα,α‐dialkylated glycines. I. A conformational energy computation and x‐ray diffraction study of homo‐peptides from Cα,α‐diethylglycine

Stereochemical Control of Peptide Folding

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Structural versatility of peptides from C^α,α‐dialkylated glycines. I. A conformational energy computation and x‐ray diffraction study of homo‐peptides from C^α,α‐diethylglycine