Molten globule intermediates and protein folding

1991 ◽  
Vol 19 (5) ◽  
Author(s):  
H. Christensen ◽  
R.H. Pain

What is the basis for the two-state cooperativity of protein folding? Since the 1950s, three main models have been put forward. 1. In ‘helix-coil’ theory, cooperativity is due to local interactions among near neighbours in the sequence. Helix-coil cooperativity is probably not the principal basis for the folding of globular proteins because it is not two-state, the forces are weak, it does not account for sheet proteins, and there is no evidence that helix formation precedes the formation of a hydrophobic core in the folding pathways. 2. In the ‘sidechain packing’ model, cooperativity is attributed to the jigsaw-puzzle-like complementary fits of sidechains. This too is probably not the basis of folding cooperativity because exact models and experiments on homopolymers with sidechains give no evidence that sidechain freezing is two-state, sidechain complementarities in proteins are only weak trends, and the molten globule model predicted by this model is far more native-like than experiments indicate. 3. In the ‘hydrophobic core collapse’ model, cooperativity is due to the assembly of non-polar residues into a good core. Exact model studies show that this model gives two-state behaviour for some sequences of hydrophobic and polar monomers. It is based on strong forces. There is considerable experimental evidence for the kinetics this model predicts: the development of hydrophobic clusters and cores is concurrent with secondary structure formation. It predicts compact denatured states with sizes and degrees of disorder that are in reasonable agreement with experiments.


1993 ◽  
Vol 2 (6) ◽  
pp. 869-876 ◽  
Author(s):  
Doug Barrick ◽  
Robert L. Baldwin

Our recent experiments on the molten globule state and other protein folding intermediates lead to following conclusions: (i) the molten globule is separated by intramolecular first-order phase transitions from the native and unfolded states and therefore is a specific thermodynamic state of protein molecules; (ii) the novel equilibrium folding intermediate (the ‘pre-molten globule’ state) exists which can be similar to the ‘burst’ kinetic intermediate of protein folding; (iii) proteins denature and release their non-polar ligands at moderately low pH and moderately low dielectric constant, i.e. under conditions which may be related to those near membranes.


Biochemistry ◽  
1994 ◽  
Vol 33 (16) ◽  
pp. 4903-4909 ◽  
Author(s):  
Ichiro Nishii ◽  
Mikio Kataoka ◽  
Fumio Tokunaga ◽  
Yuji Goto

2002 ◽  
Vol 16 (3-4) ◽  
pp. 361-370 ◽  
Author(s):  
Irena Matecko ◽  
Norbert Müller ◽  
Rita Grandori

This paper summarizes recent findings from our group concerning applications of electrospray-ionization mass spectrometry (ESI-MS) to the study of protein folding. Nano-ESI-MS was employed for the investigation of protein conformational states under varying solvent conditions and at varying values of the instrumental parameters. The effect of trifluoroethanol (TFE) on a peptide and acid-unfolded cytochromec(cytc), monitored by circular dichroism (CD) and time-of-flight ESI-MS, illustrates the specificity of the latter technique for features of protein tertiary structure. Measurements on marginally stable protein states indicate that it is possible to identify operational conditions for nano-ESI-MS in which none of the instrumental parameters limits conformational stability in the protein sample. Results described here show that changes in the charge-state distributions (CSDs) under controlled conditions allow not only discriminating between native and denatured states, but also monitoring minor conformational changes, like the transition from molten globule to native state. These studies underscore the potential of mass spectrometry methods for the analysis of heterogeneous samples and, in particular, for the characterization of dynamic equilibria involving different conformational states.


FEBS Letters ◽  
1990 ◽  
Vol 262 (1) ◽  
pp. 20-24 ◽  
Author(s):  
O.B. Ptitsyn ◽  
R.H. Pain ◽  
G.V. Semisotnov ◽  
E. Zerovnik ◽  
O.I. Razgulyaev

Nature ◽  
1991 ◽  
Vol 352 (6330) ◽  
pp. 36-42 ◽  
Author(s):  
Jörg Martin ◽  
Thomas Langer ◽  
Raina Boteva ◽  
Andrea Schramel ◽  
Arthur L. Horwich ◽  
...  

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