Some features of the optical rotatory dispersion spectrum of the α-lytic protease of Sorangium sp.

1969 ◽  
Vol 47 (3) ◽  
pp. 317-321 ◽  
Author(s):  
G. M. Paterson ◽  
D. R. Whitaker
Keyword(s):  
Optical Rotation ◽  
Substrate Binding ◽  
Cotton Effect ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Kinetic Properties ◽  
Optical Rotatory ◽  
Cotton Effects ◽  
Ph Dependent

A study of the kinetic properties of the α-lytic protease of Sorangium sp. indicated that substrate-binding by the enzyme was not pH dependent. In agreement with this indication of a pH-insensitive conformation, the optical rotation of the enzyme between pH 5 and 10.5 is not pH dependent. The optical rotatory dispersion spectrum above 220 mμ shows a main Cotton effect with a trough at 230 mμ and small but well-marked Cotton effects between 260 and 300 mμ. The reduced, mean residue rotation at the trough of the main Cotton effect was estimated to be −1650 ± 80° cm2/dmole; the Moffitt–Yang parameter b0 for rotations above 325 mμ is approximately zero. These values suggest that the enzyme has virtually no α-helices.

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

1965 ◽  
Vol 43 (5) ◽  
pp. 1588-1598 ◽  
Author(s):  
Gerald D. Fasman ◽  
Margarete Landsberg ◽  
Manuel Buchwald
Keyword(s):  
Wavelength Range ◽  
Cotton Effect ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Helical Conformation ◽  
Optical Rotatory ◽  
Negative Cotton Effect ◽  
Cotton Effects ◽  
The Right ◽  
Tryptophanyl Residue

The synthesis of high molecular weight (100 000 to 200 000) polymers and copolymers of L-tryptophan and γ-benzyl-L-glutamate is reported. The optical rotatory dispersion (o.r.d.) of these polypeptides is recorded in the wavelength range 540–320 mμ and the b0 values of the Moffitt equation, using λ0 = 212ν, are listed. Poly-L-tryptophan has a b0 value of +570 in dimethylformamide (DMF). A linear relationship exists between this value, b0 values of copolymers of various ratios of L-tryptophan and γ-benzyl-L-glutamate, and the value of− 670 found for poly-γ-benzyl-L-glutamate. The o.r.d. curve of a poly-L-tryptophan film, in the 330–200 mμ wavelength range, reveals two positive Cotton effects in the 270–290 mμ region and a large negative Cotton effect at 233 mμ. Thus, despite the positive b0 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. The 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 o.r.d. curves.

scholarly journals The formula for the optical rotatory dispersion of quartz

1929 ◽  
Vol 122 (789) ◽  
pp. 245-250 ◽  
Keyword(s):  
Original Work ◽  
Optical Rotation ◽  
Ultra Violet ◽  
Original Method ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Infra Red

The optical rotation of quartz has been measured over a large band of wavelengths. We have Gumlich’s original work over the range from λ = 2·140 μ to λ = 0·21935 μ , repeated and extended into the ultra-violet by Soret and Sarasin and Guye. More recently a series of accurate measurements covering the same range was published by Lowry, and then Duclaux and Jeantet gave a series of results for a range in the ultra-violet from λ = 0·30876 μ to λ = 0·1853980 μ . Finally, Lowry and Coode-Adams, having improved the accuracy of their original method, succeeded in obtaining a very accurate set of readings extending from λ = 2·5170 μ in the infra-red to λ = 0·2280 μ in the ultra-violet, reaching thus just up to the region measured by Duclaux and Jeantet. Various attempts have been made to fit these results into a formula. Gumlich found it possible to represent his results by a formula of the type ω = α 1 /λ 2 + α 2 /λ 4 + α 3 /λ 6 + α 4 /λ 8 + α 5 /λ 10 , but Kettler had almost equal success with the simpler form ω = (λ 2 α)/β.

An optical rotatory dispersion study on fibrinogen and some of its derivatives

1968 ◽  
Vol 46 (6) ◽  
pp. 617-620 ◽  
Author(s):  
William D. McCubbin ◽  
Cyril M. Kay
Keyword(s):  
Tertiary Structure ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Tryptic Digestion ◽  
Optical Rotatory ◽  
Molecular Rearrangement ◽  
The Core ◽  
Helical Content ◽  
Cotton Effects ◽  
Fibrinogen Molecule

Visible and ultraviolet optical rotatory dispersion measurements were carried out on native fibrinogen and some of its derivatives. The latter include: (1) desialicized fibrinogen, (2) a large fragment of the fibrinogen molecule produced by short tryptic digestion, (3) fibrin monomer, and (4) intermediate fibrin polymers produced by the controlled thrombin proteolysis of fibrinogen. The α-helical content of native fibrinogen was deduced as 32%, and empirical calculations suggest that there is about 14% β-structure in the molecule. Sialic acid plays no significant role in the maintenance of the secondary and tertiary structure of the native molecule. No major conformational change is associated with the thrombin proteolysis of fibrinogen, although a small increase in helical content (~5%) accompanies the staggered overlap association of fibrin monomers. The "core" resulting from the controlled tryptic digestion of fibrinogen undergoes a molecular rearrangement relative to the native molecule, such that it possesses a lower α-helical content (24%) and a higher β-form value (23%). In addition, some of the additional tyrosines in the core become encompassed in regions of greater asymmetry to give rise to small aromatic Cotton effects centered around 285 mμ.

Alkaloids of Lycopodiumlucidulum Michx. Structure and properties of alkaloid L.23

1969 ◽  
Vol 47 (3) ◽  
pp. 449-455 ◽  
Author(s):  
W. A. Ayer ◽  
B. Altenkirk ◽  
R. H. Burnell ◽  
M. Moinas
Keyword(s):  
Absolute Configuration ◽  
Cotton Effect ◽  
Ultraviolet Spectrum ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Structure And Properties ◽  
The Absolute ◽  
Related Compounds ◽  
Circular Dichroic

The minor alkaloids present among the strong bases of Lycopodiumlucidulum have been reinvestigated. Manske and Marion's alkaloid L.23 has been shown to be epimeric with lycodoline at C-12 and the nitrogen. A correlation between the two alkaloids has been achieved. The presence of a σ-coupled p interaction in the ultraviolet spectrum of lycopodine, lycodoline, and related compounds is described. A Cotton effect due to this chromophore has been detected by means of circular dichroism. The optical rotatory dispersion and circular dichroic properties of lycopodine, 12-epilycopodine, lycodoline, and alkaloid L.23 are discussed in terms of the absolute configuration assigned to these alkaloids.

scholarly journals Oligonucleotide studies. Optical rotatory dispersion of five homodinucleotides

1969 ◽  
Vol 113 (5) ◽  
pp. 843-851 ◽  
Author(s):  
Yasuo Inoue ◽  
Kimihiko Satoh
Keyword(s):  
Ionic Strength ◽  
Salt Concentration ◽  
Equilibrium Mixture ◽  
Cotton Effect ◽  
Phosphate Group ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Ionization State ◽  
Terminal Phosphate Group

1. The optical rotatory dispersion (ORD) of five homodinucleotides, ApAp(3′), CpCp(3′), GpGp(3′), IpIp(3′) and UpUp(3′) (where A, C, G, I and U represent adenosine, cytidine, guanosine, inosine and uridine respectively, and p to the left of a nucleoside symbol indicates a 5′-phosphate and to the right it indicates a 3′-phosphate), were measured as a function of pH, ionic strength and Mg2+ concentration. 2. The ORD titrations of ApAp(3′) and CpCp(3′), which were made by measuring the ORD curves at closely spaced pH intervals, exhibit a maximum at approx. pH5·0 and 5·7 for ApAp(3′) and CpCp(3′) respectively in the profile of the magnitude of the first Cotton effect versus pH. The results indicate that the conformational rigidity of these dinucleotides depends on the ionization state of a 3′-terminal phosphate group. 3. ApAp(3′) was shown to exist as an approximately 1:1 equilibrium mixture of the two major ionic species represented by Ap(−1)Ap(−1) and Ap(−1)Ap(−2) at pH6·16, whereas at pH7·5 it exists exclusively as a form of Ap(−1)Ap(−2). 4. To ascertain the effects of the presence of a terminal phosphate group and of the ionization of the secondary phosphate on the conformation of adenylate dimer, we measured the ORD of ApA, ApAp(3′)CH3 and ApAp(2′). The rotatory power of the first Cotton effect in the above series of dinucleotides decreased at 20° in the order ApA> ApAp(3′)CH3≈ApAp(3′)(−1)> ApAp(2′) at pH7> ApAp(3′) at pH7. 5. The pH–rotation profiles were also obtained for ApAp(2′), CpCp(2′) and UpUp(3′), but no corresponding maximum was observed. Although simple nearest-neighbour calculations based on the ORD data of IpIp(3′) and 5′-IMP account for the observed ORD spectrum of polyinosinic acid at low salt concentration, there were large discrepancies between calculated and experimental results of the polyguanylic acid ORD even at low ionic strength. 6. The extent to which the amplitude of the Cotton effects of IpIp(3′) increases with salt concentration, especially by the addition of Mg2+, was much greater than that observed for ApAp(3′). The implication of such salt effects on the ORD is considered.

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