Investigation of the α‐Helix—Random‐Coil Transition in Polyglutamic Acid by Slow Neutron Scattering

1966 ◽  
Vol 44 (8) ◽  
pp. 3127-3128 ◽  
Author(s):  
H. Boutin ◽  
W. L. Whittemore
Keyword(s):  
Neutron Scattering ◽  
Slow Neutron ◽  
Random Coil ◽  
Polyglutamic Acid ◽  
Coil Transition ◽  
Α Helix

CONFORMATION AND PHASE TRANSITION OF POLY-GLUTAMINE

2006 ◽  
Vol 17 (02) ◽  
pp. 235-246 ◽  
Author(s):  
GÖKHAN GÖKOĞLU ◽  
TARIK ÇELİK
Keyword(s):  
Low Temperatures ◽  
Low Energy ◽  
Random Coil ◽  
Polyglutamine Diseases ◽  
Aggregate Formation ◽  
Two Phase ◽  
Coil Transition ◽  
Energy Stable ◽  
Α Helix ◽  
Β Sheet

In order to provide insights into the misfolding mechanism and the subsequent aggregate formation which cause what are known as the neurodegenerative polyglutamine diseases, we have simulated a 10-residue polyglutamine (poly-Q) chain in vacuum and in solvent by multicanonical method, which enabled us to study the system in a wide temperature range and discuss thermodynamic properties. It is understood that the system in vacuum shows two phase transitions, first of them occur at high temperature that is the well-known helix-coil transition and the second one is a solid-solid transition. However, the poly-Q chain in solvent is in a random coil state at higher temperatures, goes through a conformational change at T = 200 K and assumes predominantly a mixture of anti-parallel β-sheet and α-helix structures at low temperatures. One-residue glutamine dipeptide is also simulated and low-energy stable conformations are identified.

Intramolecular α-helix-β-structure-random coil transition in polypeptides

1982 ◽  
Vol 16 (4) ◽  
pp. 275-285 ◽  
Author(s):  
Hiromitsu Wakana ◽  
Takao Shigaki ◽  
Nobuhiko Saitô
Keyword(s):  
Random Coil ◽  
Coil Transition ◽  
Α Helix

scholarly journals Contractility and Conformation

1967 ◽  
Vol 50 (6) ◽  
pp. 5-27 ◽  
Author(s):  
Harold A. Scheraga
Keyword(s):  
Partition Function ◽  
Mechanical Treatment ◽  
Random Coil ◽  
Dilute Solution ◽  
Factors Affecting ◽  
Macromolecular Conformation ◽  
Counting Procedure ◽  
Coil Transition ◽  
Statistical Mechanical ◽  
Α Helix

Contractility in fibers can arise from changes of macromolecular conformation caused by changes in some thermodynamic variable such as temperature, pH, or solvent composition. Illustrations are given of contractile processes in fibers and of changes in macromolecular conformation in dilute solution. These may involve order-disorder transitions, e.g. of the type exhibited by the helix-coil transition. A statistical mechanical treatment of the helix-coil transition involves the assignment of statistical weights to various states and the proper counting of these statistical weights in the formation and evaluation of the partition function; the thermodynamic properties of the system are derivable from the partition function. The counting procedure involved in the consideration of the α-helix and random coil is described. In addition, the factors affecting the relative stabilities of various helical conformations are discussed. These considerations of macromolecular conformation provide a basis for discussing contractile mechanisms in which changes of conformation are involved.

Intramolecular α-helix-β-structure-random coil transition in polypeptides

1982 ◽  
Vol 16 (4) ◽  
pp. 287-295 ◽  
Author(s):  
Hiromitsu Wakana ◽  
Nobuhiko Saitô
Keyword(s):  
Random Coil ◽  
Coil Transition ◽  
Α Helix
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