|
|
| (One intermediate revision by one other user not shown) |
| Line 1: |
Line 1: |
| '''Helix–coil transition models''' are formalized techniques in [[statistical mechanics]] developed to describe [[conformation (chemistry)|conformation]]s of linear [[polymer]]s in solution. The models are usually but not exclusively applied to [[polypeptide]]s as a measure of the relative fraction of the molecule in an [[alpha helix]] conformation versus [[turn (biochemistry)|turn]] or [[random coil]]. The main attraction in investigating [[alpha helix]] formation is that one encounters many of the features of [[protein folding]] but in their simplest version.<ref name="Doig2008">{{cite book
| | They call me Emilia. What I love doing is doing ceramics but I haven't produced a dime with it. Managing people is what I do and the salary has been truly fulfilling. My family life in Minnesota and my family loves it.<br><br>Also visit my website :: [http://www.youporn-nederlandse.com/user/CMidgett home std test] |
| |author=Doig AJ
| |
| |year=2008
| |
| |chapter=The alpha-Helix as the Simplest Protein Model: Helix–Coil Theory, Stability, and Design
| |
| |title=Protein Folding, Misfolding and Aggregation: Classical Themes and Novel Approaches
| |
| |editor= Muñoz V
| |
| |publisher=Royal Society of Chemistry
| |
| }}</ref> Most of the helix–coil models contain parameters for the likelihood of helix [[nucleation]] from a coil region, and helix propagation along the sequence once nucleated; because polypeptides are directional and have distinct [[N-terminus|N-terminal]] and [[C-terminus|C-terminal]] ends, propagation parameters may differ in each direction.
| |
| | |
| The two states are
| |
| * helix state: characterized by a common rotating pattern kept together by [[hydrogen bond]]s, (see [[alpha-helix]]).
| |
| * coil state: conglomerate of randomly ordered sequence of atoms (see [[random coil]]).
| |
| | |
| Common transition models include the [[Zimm-Bragg model]] and the [[Lifson-Roig model]], and their extensions and variations.
| |
| | |
| Energy of host poly-alanine helix in aqueous solution:
| |
| :<math>
| |
| \Delta G_{folding} = (m-2)\Delta H_\alpha - m T \Delta S
| |
| </math>
| |
| where ''m'' is number of residues in the helix.<ref name="Chakrabartty1995">{{cite journal
| |
| |doi=10.1016/S0065-3233(08)60334-4
| |
| |author=Chakrabartty A, Baldwin RL
| |
| |year=1995
| |
| |title=Stability of alpha-helices
| |
| |journal=Adv Protein Chem
| |
| |volume=46
| |
| |pages=141–176
| |
| |pmid=7771317
| |
| }}</ref>
| |
| | |
| ==References==
| |
| {{reflist}}
| |
| | |
| {{DEFAULTSORT:Helix-coil transition model}}
| |
| [[Category:Protein structure]]
| |
| [[Category:Statistical mechanics]]
| |
| [[Category:Thermodynamics]]
| |
| | |
| | |
| {{physics-stub}}
| |
They call me Emilia. What I love doing is doing ceramics but I haven't produced a dime with it. Managing people is what I do and the salary has been truly fulfilling. My family life in Minnesota and my family loves it.
Also visit my website :: home std test