Circular Dichroism of Poly-L-tyrosine<sup>*</sup>

Beychok, Sherman; Fasman, Gerald D.

doi:10.1021/bi00899a012

Cited by 149 publications

(52 citation statements)

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“…Such 0.r.d. and circular dichroisin studies of poly-L-tyrosine (18,19) in aqueous media revealed this negative Cotton effect and circular dichroic band, further confirming the right-handed sense of the helix of this polymer. The optical rotation of solutions of poly-L-tryptophan in DXIF could only be determined do\\;n to 300 inp because of the absorbance of the solvent, and no other transpareilt helix-promoting solvent for this polymer could be found.…”

Section: E X C Obtained From a Drude Plotmentioning

confidence: 61%

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CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

Fasman¹,

Landsberg²,

Buchwald³

1965

Can. J. Chem.

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The synthesis of high n~olecular weight (100 000 to 200 000) polymers and copolymers of L-tryptophan and y-benzyl-L-glutamate is reported. The optical rotatory dispersion (0.r.d.) of these polypeptides is recorded in the wavelength range 540-320 mp and the bo values of the Moffitt equation, using X O = 212 mp, are listed. Poly-L-tryptophan has a bo value of f 570 in dimethylforman~ide (DMF). A linear relationship exists between this value, bo values of copolymers of various ratios of L-tryptophan and y-benzyl-L-glutamate, and the value of -670 found for poly-r-benzyl-~-glutamate. T h e 0.r.d. curve of a poly-L-tryptophan film, in the 330-200 mp wavelength range, reveals two positive Cotton effects in the 370-290 m p region and a large negative Cotton effect a t 233 mp. Thus, despite the positive bo value, these data prove that poly-L-tryptophan, in DMF, has the right-handed helical conformation. Hypochromicity was found for the tryptophanyl residue in the helical polypeptide. T h e rotatory contribution of chromophores, such as tryptophan or coenzymes, when bound asymmetrically to a protein, can be very significant, and caution is advised in the interpretation of such 0.r.d. curves.Optical rotatory dispersion (0.r.d.) measurements have become extensively used to determine the conformation of proteins (1, 2, 3). The anomalous rotatory dispersion curves for many synthetic poly-a-amino acids and proteins in the helical conforn~ation have been adequately interpreted by the Moffitt equation (4, 5) [nz1]x = aoXo2/(X" Xo2) + bOXo4/(X2 -kg2)?. Although it is acknowledged that this treatment of 0.r.d. data is of a highly empirical nature, the constant bo in this equation has been successfully used as a measure of the helical content in polypeptides and proteins. The bo value of approximately -630 to -670 (XO = 212 mp) has been found for the 100% right-handed helical conformation (5, 6), while the random coil form has a bo value of zero (6). The sign of the bo has been taken to indicate the sense of helix, and has been corroborated by X-ray studies (7). Estimates of helical content derived from 0.r.d. data (8, 9) agree remarkably well with X-ray data for myoglobin (10). More recently a modified Drude equation (11) has been proposed to estimate helical contents in polypeptides based on 0.r.d. studies penetrating further into the ultraviolet region. However, this treatment is theoretically inadequate, as a new Cotton effect has since been discovered (Holzwarth and Doty (12) have shown that the 233 mp Cotton effect is a composite of two such bands and that two circular dichroism bands are responsible for this Cotton effect, one caused by a n -+ n* transition and the other caused by a n -+ n* transition), which liltewise places

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Section: E X C Obtained From a Drude Plotmentioning

confidence: 61%

“…However, poly-L-tyrosine was sho\vn by 0.r.d. studies (17,18) and circular dichroism (19) studies to be a right-handed helix. Consequently, the positive bo value must be due to the contribution of the chroinophoric side chains on the P-carbon which contributes to the rotation in the visible region of the spectrum.…”

mentioning

confidence: 99%

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

Fasman¹,

Landsberg²,

Buchwald³

1965

Can. J. Chem.

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“…The optical rotatory properties of poly-L-tyrosine or tyrosine-rich peptide (TRP) have been reported to be very different from those of common peptides [47][48][49][50][51][52][53][54] . A TRP with a right-handed a-helical conformation has four p-p* side-chain transitions (analogous to the A 1g , B 1u , B 2u and E 1u states of benzene) at about 200, 230 and 280 nm in neutral aqueous solution [51][52][53] .…”

Section: Resultsmentioning

confidence: 99%

Tyrosine-mediated two-dimensional peptide assembly and its role as a bio-inspired catalytic scaffold

et al. 2014

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In two-dimensional interfacial assemblies, there is an interplay between molecular ordering and interface geometry, which determines the final morphology and order of entire systems. Here we present the interfacial phenomenon of spontaneous facet formation in a water droplet driven by designed peptide assembly. The identified peptides can flatten the rounded top of a hemispherical droplet into a plane by forming a macroscopic two-dimensional crystal structure. Such ordering is driven by the folding geometry of the peptide, interactions of tyrosine and crosslinked stabilization by cysteine. We discover the key sequence motifs and folding structures and study their sequence-specific assembly. The well-ordered, densely packed, redox-active tyrosine units in the YYACAYY (H-Tyr-Tyr-Ala-Cys-Ala-Tyr-Tyr-OH) film can trigger or enhance chemical/electrochemical reactions, and can potentially serve as a platform to fabricate a molecularly tunable, self-repairable, flat peptide or hybrid film.

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“…FAD [37], iron [38], copper [19] or molybdenum [38] complexes. I n the spectral region of 230 to 310-nm Cotton effects originating from cofactors are superimposed by those caused by side chain residues of amino acids like L-cystine [39], L-phenylalanine [39], L-tyrosine [40] or L-tryptophan [41,42]. The Cotton effects of the peptide bonds are located in the spectral region of 185-230 nm [43 to 461.…”

Section: Interpretation Of Circular-dichroism Datamentioning

confidence: 99%

Characterization of Cd, Zn‐Thionein (Metallothionein) Isolated from Rat and Chicken Liver

Weser

Rupp

Donay

et al. 1973

European Journal of Biochemistry

201

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The preparation of pure metallothionein from Cd-pretreated rats and chicken was performed using short-time treatment with chloroformlethano1 followed by ion-exchange and gel chromatography. The protein contained 7 g-atoms metal ions per 12000 g protein. The Zn to Cd ratio was 1 :2.4 f 0.1. The Cd, Zn-thionein remained homogeneous during Sephadex G-25, 6-50 and 6-75 gel filtration, during polyacrylamide disc-gel electrophoresis and in the analytical ultracentrifuge. The high content of cysteine residues (approx. one-third of the total residues) was consistent with the cysteine content of metallothionein isolated from human or equine tissues. The Cd, Znthionein was of considerable temperature stability. The physicochemical properties were examined by ultraviolet spectroscopy, circular dichroism (CD) measurements and X-ray photoelectron spectroscopy. The millimolar absorption coefficient of the native protein was a t 250nm ~2543 = 80.6 mM-1-cm-1. Virtually no aromatic amino acids were present. The E~~~ value of the apoprotein prepared by metal displacement using HC1 was E~~~ = 13.2 mM-1 * cm-l. When the ultraviolet spectrum of the apoprotein was recorded a t p H 6.6 a distinct peak was detectable at 255 nm (eZ5,, = 18.7 m M-1. om-l). The existence of inter-or intramolecular disulphide formation was confumed by CD measurements employing the polyethyleneglycol esters of di-tert-butyloxycarbonyl-L-cystine and tert-butyloxycarbonyl-L-cysteine as model aompounds for high-molecularweight and water-soluble cysteine compounds, respectively.From CD data it was concluded that Cd, Zn-thionein exists mainly as a random-coil peptide.Some indication of the binding of Cd and Zn in the native protein with eS-R moieties was obtained from ultraviolet data. Final proof of the exclusive coordination of these metal ions with cysteine sulphur was successful using both circular dichroism measurements and especially X-ray photoelectron spectroscopy. The last method proved most convenient for determining the binding energies of the core electrons of Cd (Cd 3d,,= = 411.0 eV and Cd 3d,ll = 404.4 eV), Zn (2 pal, =1021.0 eV) and S (2p = 161.7 eV). The corresponding binding energies for S in the cystine complexes with Zn2+ and Cd2+ were 163.0 eV and 162.8 eV, respectively.Sixteen years ago Margoshes andVallee were able to demonstrate the simultaneous presence of Cd, Zn and even Hg in a protein isolated from kidney cortex sulphur-containing amino acids, it was suggested the protein be named metallothionein. At the moment the discussion regarding the biochemical function of metallothionein is still going on. One important action would appear rather attractive : the decontamination of biological systems from harmful mercury and cadmium ions. This hypothesis has been supported by the observation of a rapid rise of metallothinein synthesis following the oral or intraperiotoneal administration of cadmium to rabbits [5,6], rats [7 to 91 and chicken [10,11].Although our knowledge of metauothionein is quite established, there is still considerable work ...

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Circular Dichroism of Poly-L-tyrosine^*

Cited by 149 publications

References 10 publications

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

Tyrosine-mediated two-dimensional peptide assembly and its role as a bio-inspired catalytic scaffold

Characterization of Cd, Zn‐Thionein (Metallothionein) Isolated from Rat and Chicken Liver

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Circular Dichroism of Poly-L-tyrosine*

Cited by 149 publications

References 10 publications

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

Tyrosine-mediated two-dimensional peptide assembly and its role as a bio-inspired catalytic scaffold

Characterization of Cd, Zn‐Thionein (Metallothionein) Isolated from Rat and Chicken Liver

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Circular Dichroism of Poly-L-tyrosine^*