Conformational studies of proteins with aromatic side‐chain effects

Goodman, Murray; Toniolo, Claudio

doi:10.1002/bip.1968.360061202

Cited by 69 publications

(39 citation statements)

References 64 publications

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“…39 -41 However, this conformational conclusion is not unambiguous, in view of the presence of one (or two) substituted phenyl moiety(ies) in the side chain of each crowned Mdp residue whose transitions are expected to overlap those of the peptide chromophores. 42 Support for this cautionary note is also given by the abnormally high ellipticity values observed in the spectral range examined. It is evident that this tentative proposition should be confirmed by other chirospectroscopic techniques (e.g., vibrational CD) that are insensitive to the presence of aromatic chromophores in the peptide molecules.…”

Section: Circular Dichroismmentioning

confidence: 90%

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

et al. 2003

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The preferred conformation of five, terminally protected, model peptide series to the hexamer level, based on three novel crowned, C(alpha)-methyl L-DOPA amino acids combined with either L-Ala/Aib or Gly/Aib, were assessed in structure supporting solvents using FT-IR absorption, (1)H NMR, and CD techniques. The FT-IR absorption spectra strongly suggest that the contribution of the crowned C(alpha)-tetrasubstituted residue to intramolecular H-bonding is equivalent to that of Aib and is much more significant than that of either L-Ala or Gly. In addition, the (1)H NMR titrations and the CD patterns resemble those typically exhibited by (right-handed) 3(10)-helical structures.

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Section: Circular Dichroismmentioning

confidence: 90%

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

et al. 2003

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“…This pattern is indicative of a predominantly unordered conformation [22]. Very small Cotton effects, associated with the aromatic chromophores of phenylalanyl, tyrosyl and tryptophanyl residues, were observed in the 250-300-nm region [23]. No circular dichroism was apparent for the apoprotein and the apo-(1 -65) fragment above 300 nm.…”

Section: Circular Dichroism Studiesmentioning

confidence: 99%

Conformational Studies of Equilibrium Structures in Fragments of Horse Heart Cytochrome c

Toniolo¹,

Fontana²,

Scoffone³

1975

European Journal of Biochemistry

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Ultraviolet absorption and circular dichroism studies have been carried out on horse heart apo-cytochrome c and heme-free peptide fragments obtained by cyanogen bromide cleavage of the native protein. It was noted that the various peptides assume predominantly an unordered conformation in water solution. Increasing ionic strength and addition of 2-chloroethanol increase the right-handed helical content. Guanidinium hydrochloride favors the coil state. It was also demonstrated that two non-interacting helical regions of different stability are present in the apoprotein in 2-chloroethanol.One of the major problems in modern protein chemistry is the determination of the mechanisms by which polypeptide chains fold during biosynthesis or renaturation [I -31. In particular, studies in this field would help to clarify the relative contribution of thermodynamic and kinetic factors in determining protein conformation and the nature of the forces involved [4-61.Native proteins carrying components which are not amino acids, such as heme, flavin and pyridine nucleotides, that are required for the self-assembly process. appear to pose additional problems.Our approach to this problem is to investigate by physico-chemical techniques the equilibrium structures in protein fragments obtained by synthesis or chemical and enzymatic cleavages [3].In this paper we report a conformational analysis of horse heart apo-cytochrome c and heme-free peptide fragments obtained by cyanogen bromide cleavage of the native protein [7-1 I]. EXPERIMENTAL PROCEDURE MaterialsHorse heart cytochrome c (type 111) was obtained from Sigma and used without further purification. Cyanogen bromide, 2-mercaptoethanol and silver sul-Ahhrc.riution. CD, circular dichroism. fate were Fluka products. N-Acetyl-L-tyrosinamide and N-acetyl-L-tryptophanamide were purchased from Sigma. 2-Chloroethanol and ethylene glycol (Fluka) were of the highest purity commercially available and were used without further purification. Iodoacetic acid (Merck), Tris (Fluka) and 98 -100 ; / , formic acid (Merck) were also used without further purification. Sephadex G-25 and G-50 both superfine were obtained from Pharmacia Fine Chemicals and preswollen microgranular carboxymethyl (CM) cellulose (Whatman CM-52) was purchased from Reeve Angel. MethodsAmino acid analyses were performed according to standard techniques [12] on a C. Erba amino acid analyzer, model 3A27. Acid hydrolyses were carried out in 6 N HCI in evacuated tubes sealed under vacuum in presence of phenol (0.1 "/). Free sulfhydryl groups were measured by S-carboxymethylation with iodoacetic acid followed by acid hydrolysis [ 131. The pH values were measured with a Radiometer pH meter, model 29.The refractive indexes were determined using an Abbe refractometer (Galileo, Milan).Thin-layer chromatography was performed on cellulose plates (Merck) with 1 -butanol-pyridineacetic acid -water (10 : 15 : 3 : 12, by vol.) as eluent. Peptides were detected by ninhydrin spray (0.2 in acetone) or by the hypochlorite starch-iodide chrom...

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“…Also, i~si~ally the measurements did not penetrate in the region of T --' , T * peptide transition (24). Notwithstanding the well-established superiority of cd over ord and the rclcvant amount of information which one can obtain from the spectral region below 220 nm (24) o~ily two papers have appeared with the explicit purpose of detcrmining the cd spectra to 190 nm of amino acid residues (2) or peptide chromophores2 occupying an internal position in a randomly coiled polypeptide chain.…”

Section: Resultsmentioning

confidence: 89%

“…The cd spectra of L-Ala-L-Ala, L-Nva-L-Nva, and L-Leu-L-Leu internal peptide chromophores are characterized by two negative bands of different intensities centered at about 220 1lm (n + Z* amide transition) (24) and 198 nil1 (Z -> Z* ainide transition) (24), respectively (Fig. 1) spectrum of phenylalanine pepis mainly due t o the fact that the negative a -> a* tides (8), is assigned to a n overlapping of the two cd band is rlluch less intense for L-Val-L-Val and more intellse s~lort-wavelengt~l bands o~o p p o s~t e L-lle-L-Ile.…”

Section: Iizterizal Peptide Chrotnophore Circular Dichroistn Of Peptimentioning

confidence: 99%

Linear oligopeptides. XXVII. Contribution to the circular dichroism of internal peptide chromophores

Toniolo¹,

Bonora²

1976

Can. J. Chem.

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-l~cxall~1oropro~~a1~-2-ol were calci~lated by subtracting the total molar ellipticity values of N-and C-protected homo-trimers from those of the pertinent protected homo-tetramers.The circular dichroism of the internal peptide chromophore of aliphatic hydrocarbon-and s~llfur-containing peptides, each of the L-configuration, show a negative band at 21 5-230 nm accompanied by a more intense negative band near 200 nm. A structi~red wcak and negative band near 260 nm along with bands at 240 nm (negative), 222 nm (positive), and 210.5 nm (negative) of progressively increasing intensity are apparent in the circular dichroic spectrilln of L-Phe-L-Phe internal peptide chro~nophore. The elfect of solvent polarity is discilssed in thc case of L-Val-L-Val and L-Ala-L-Ala internal peptide chromophores.Among the protected ho~no-trimers and tetramers only those of L-alanine are soluble in aqileoils solution; consequently, the effect of water as a function of temperature, urea, and guanidinium chloride on the L-Ala-L-Ala internal peptide chromophore circular dichroism was established.CLAUDIO TONIOLO et GIAN MARIA BONORA. Can. J. Chem. 5'470 (1976). On a calci~le la contribution des chro~nophores peptidiques internes ail dichroismc circillaire Parmi les homo trimkres et tetramkres protCgCs seulement cells de la L-alaninc sont solubles dans des solutions aqueuses; par consCquent I'effet dc I'ea~i cn fonction de la temperature,

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Conformational studies of proteins with aromatic side‐chain effects

Cited by 69 publications

References 64 publications

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

Conformational Studies of Equilibrium Structures in Fragments of Horse Heart Cytochrome c

Linear oligopeptides. XXVII. Contribution to the circular dichroism of internal peptide chromophores

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Conformational studies of proteins with aromatic side‐chain effects

Cited by 69 publications

References 64 publications

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, Cα‐methyl L‐DOPA amino acids

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, Cα‐methyl L‐DOPA amino acids

Conformational Studies of Equilibrium Structures in Fragments of Horse Heart Cytochrome c

Linear oligopeptides. XXVII. Contribution to the circular dichroism of internal peptide chromophores

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New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids

New tools for the control of peptide conformation and supramolecular chemistry: Crown‐carrier, C^α‐methyl L‐DOPA amino acids