Universal kinetics of helix-coil transition in gelatin.
By covering a much wider concentration range than previous studies we find a very unusual exponential dependence of the rate of helix formation on concentration of gelatin in water and ethylene glycol solutions. By applying a procedure of concentration-temperature superposition we build a master curve describing the initial renaturation rates in both solvents. The growth of the normalized helical fraction chi(t) is a first-order process, with a rate constant consistent with cis-trans isomerization, in most situations. We propose that association of three separate chains to form a triple helical nucleus occurs rapidly and contributes less to the helical onset than previously thought. The measured helix content is a result of lengthening of the triple helix after nucleation, by zipping from the associated nuclei.
Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3OHE, United Kingdom.
J L
JL
Gornall
E M
EM
Terentjev
D019295:Computational Biology / Q000379:methods*; D019855:Ethylene Glycol / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D017510:Protein Folding; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry
D012996:Solutions; D012997:Solvents; D014867:Water; D005780:Gelatin; D019855:Ethylene Glycol