Optical rotation of ribonuclease

Schellman, John A.; Lowe, Margaret J.

doi:10.1021/ja01006a048

Cited by 45 publications

(11 citation statements)

References 2 publications

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“…The tentative assignments refer to transitions of the peptide chromophore (cf. Beychok, 1967;Schellman and Lowe, 1968). The above bands, along with the data in Table I, give a good fit to the experimental CD spectrum over the wavelength interval 192-320 nm, although as discussed in the text little physical meaning can be attached to the far-ultraviolet bands.…”

Section: Resultsmentioning

confidence: 71%

“…data did not extend below 210 nm. At all wavelengths the ellipticity of RNase P is somewhat less than the corresponding value for RNase A3 (Schellman and Lowe, 1968;Tamburro et al, 1968a;Pflumm and Beychok, 1969;Klee and Streaty, 1970).…”

Section: Resultsmentioning

confidence: 71%

“…Rotational strengths and tentative band assignments are given in Table II. Clearly, these bands represent a definite minimum (Schellman and Lowe, 1968) since complete resolution would necessitate introduction of n-7r* and tt-tt* bands associated with each conformation, e.g., a helix, ß structure, and non-helix, as well as contributions from aromatic groups and disulfides in this region. For these reasons the far-ultraviolet band parameters in Table II should be viewed simply as curve characterization parameters with little emphasis being placed on a molecular interpretation.…”

Section: Resultsmentioning

confidence: 99%

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Conformation and conformational stability of ribonuclease A and its peptic derivative, des-(121-124)-ribonuclease

Puett¹,

Wasserman²,

Friebele³

1972

Biochemistry

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We have determined the near-ultraviolet circular dichroic spectrum (235-315 nm) and the ultraviolet difference absorption spectrum of ribonuclease A (RNase A) and its peptic derivative, des-(121-124)-RNase A (RNase P), which is missing the four C-terminal residues and retains no more than a few per cent of the enzymic activity of RNase A. The circular dichroic spectra of both proteins were resolved into gaussian parameters and the rotational strengths of the resolved bands (due mainly to tyrosines and disulfides) were found to be very similar in the two proteins. Also, the denaturation difference spectrum was almost identical, thus indicating that in each native protein the same number of tyrosyl groups are inaccessible to solvent. The circular dichroic spectrum of RNase P between 195 and 235 nm was also obtained and compared to the known spectrum of RNase A. The gen-

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Conformation and conformational stability of ribonuclease A and its peptic derivative, des-(121-124)-ribonuclease

Puett¹,

Wasserman²,

Friebele³

1972

Biochemistry

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“…For example the a-helical structure is characterized by a negative Cotton effect a t about 233 nm [6] which is not apparent in the neurotoxin spectrum. It is difficult to interpret optical rotatory dispersion spectra in terms of mixtures of the standard structures because of Cotton effects arising from the aromatic chromophores and disulphide bridges [7,8] in globular proteins.…”

Section: Resultsmentioning

confidence: 99%

The Conformation of Small Proteins

Chicheportiche

Lazdunski

1970

European Journal of Biochemistry

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The conformation of neurotoxin I1 of Androctonus Australis Hector has been studied by optical rotatory dispersion and ultraviolet difference spectrophotometry. Depending upon pH and temperature, the protein exists under, a t least, four different molecular forms, I , 11, I11 and D which are in rapid equilibrium.A state-diagram has been obtained which describes the different zones of temperature and pH in which forms I, 11, I11 and D are stable. A physico-chemical analysis of all transconformations has been carried out. The acidic as well as the alkaline transition (I $ I1 and I $ I11 respectively) are controlled by the unmasking of structurally important ionisable groups, one of them being probably the carboxylic side-chain of an aspartic or a glutamic acid. Form I , which is predominant between pH 4 and 9 and below 30", contains a high degree of ordered structure. It is very stable toward heat denaturation and remains folded in 9.5 M urea, while form 11, its conformational isomer a t acidic pH, is completely unfolded a t 50" or in high concentrations of urea. A very low cooperativeness has been observed for the unfolding of form I1 in urea or a t high temper- In view of the small size and unusual biological function of these proteins, it is worthwhile to obtain some information about their conformation in solution. This is one necessary step toward the determination of structure-function relationships. The primary structure of toxin I and the N-terminal sequence of 42 amino acids of toxin I1 are now known [5]. This conformational analysis of neurotoxin I1 ofAndroctonus Australis Hector is part of a more general study of the physico-chemical properties of small proteins (58 to 80 amino acids). MATERIALS AND METHODSPreparation of the Neurotoxin Neurotoxin I1 was purified from the venom of Androctonus Australis Hector as previously described by Rochat et al. [4]. The protein was shown to be homogeneous by equilibrium chromatography on Amberlite CG-50, by starch gel and disc electrophoresis, by determination of the N-terminal sequence and by ultracentrifugation. Toxicity was measured by intraveinous injection to 20g mice; L.D.,, was 10 pg/kg mice [4]. Optical Rotatory Dispersion, Ultraviolet SpectrophotometryOptical rotatory dispersion measurements were carried out in a Fica "Spectropol 1" spectropolarimeter. The cell could be thermostated between 5" The mean residue weight (MRW) was 115 for the neurotoxin.Spectrophotometric determinations were made in a Cary 14 spectrophotometer. The jacketed 10mm path cell could be thermostated between 5" and 85" with a precision of 0.2".All melting curves of neurotoxin I1 were obtained in the presence of 0.1 M NaCl and 10 mM glycine.Acetate, 2 -(N-morp holino ) ethane sulfonic acid, N-tris (hydroxymethyl) methyl 2-amino ethane sulfonic acid and Tris a t a concentration of 10mM, were used to prepare buffers between pH 4 and 9. Glycine (10 mM) was used outside of this range.

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“…6 These results are from the earlier paper (Puett, 1972a). relative to the normal -helical CD -* band (Schellman and Lowe, 1968). Also, the aromatic groups may contribute to the optical activity in this region.…”

Section: Resultsmentioning

confidence: 98%