Circular dichroism studies of sheep β-lipotropic hormone

1976 ◽  
Vol 54 (11) ◽  
pp. 992-998 ◽  
Author(s):  
Serge St-Pierre ◽  
Claude Gilardeau ◽  
Michel Chrétien
Keyword(s):  
Circular Dichroism ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Conformational Transition ◽  
Acidic Solutions ◽  
Nacl Concentration ◽  
Helical Content ◽  
The Stability ◽  
Far Ultraviolet ◽  
Circular Dichroïsm

The far ultraviolet circular dichroism spectra of sheep β-lipotropic hormone (β-LPH) were recorded under different conditions of pH, temperature, salt concentration, and solvent composition. Results confirm the stability of the hormone in strong basic or acidic solutions; moreover, temperatures up to 50 °C do not seem to affect noticeably the conformation of β-LPH. However, increasing the NaCl concentration or addition of dioxane in the solution brings about a conformational transition of the chain, interpreted as an increase in the helical content. The method of Yang (Chen, Y. H., Yang, J. T. &Martinez, H. M. (1972) Biochemistry 11, 4120–4131) was used to compute the proportion of helical, β, and unordered forms of the hormone chain. The proportions are compared with those obtained from Fasman's predictive method (Chou, P. Y. &Fasman, G. D. (1974) Biochemistry 13, 211–221 and Chou, P. Y. &Fasman, G. D. (1974) Biochemistry 13, 222–245) based on the known amino acid sequence of β-LPH.

Conformational analysis of thymidylate synthase from amino acid sequence and circular dichroism

Biochemistry ◽  
1986 ◽  
Vol 25 (21) ◽  
pp. 6650-6655 ◽  
Author(s):  
Parthasarathy Manavalan ◽  
Denice M. Mittelstaedt ◽  
Michael I. Schimerlik ◽  
W. Curtis Johnson
Keyword(s):  
Circular Dichroism ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Conformational Analysis ◽  
Thymidylate Synthase ◽  
Circular Dichroïsm

Comparison of X-ray data to estimated secondary structures from amino acid sequence and circular dichroism of human prealbumin

1976 ◽  
Vol 73 ◽  
pp. 1018-1023 ◽  
Author(s):  
Jean Garnier ◽  
Roland Salesse ◽  
Berthe Rérat ◽  
Claude Rérat ◽  
Colin Blake
Keyword(s):  
Circular Dichroism ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Secondary Structures ◽  
X Ray ◽  
Circular Dichroïsm ◽  
Human Prealbumin

Synthesis and characterization of a fragment of an ice nucleation protein

1993 ◽  
Vol 71 (5-6) ◽  
pp. 236-240 ◽  
Author(s):  
Paul Ala ◽  
Pele Chong ◽  
Vettai S. Ananthanarayanan ◽  
Neville Chan ◽  
Daniel S. C. Yang
Keyword(s):  
Circular Dichroism ◽  
Synthetic Peptides ◽  
Ph Dependence ◽  
Ice Nucleation ◽  
Helical Structures ◽  
Ice Nucleation Protein ◽  
Helical Content ◽  
The Stability ◽  
Circular Dichroïsm ◽  
Ice Nucleation Proteins

Synthetic peptides were used as models for studying the conformation of ice nucleation proteins. We chemically synthesized four peptides (16-, 24-, 32-, and 48-mer) that consisted of two to six repeats of the consensus repeating octapeptide unit of ice nucleation proteins and evaluated their conformation by circular dichroism spectroscopy. These model peptides exist predominantly as random coils in aqueous solution, but adopt α-helical structures in the presence of trifluoroethanol. The stability of their secondary structures was investigated by monitoring the pH and time dependence of their circular dichroism spectra. Our results indicated that the α-helical content of the 48-mer exhibited a significant pH dependence, while that of the 24- and 32-mer peptides did not. The 32-mer was the only peptide that transformed from the α-helical to a β-sheet structure upon storage. We suggest that the overall conformation of the ice nucleation protein could be a β-sheet.Key words: ice nucleation protein, synthetic peptides, circular dichroism.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

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