Disulfide-containing proteins are ideal models for studies of protein folding as the folding intermediates can be observed, trapped, and separated by HPLC during the folding reaction. However, regulating or analyzing the structures of folding intermediates of peptides and proteins continues to be a difficult problem. Recently, the development of several techniques in peptide chemistry and biote...

In protein folding the term plasticity refers to the number of alternative folding pathways encountered in response to free energy perturbations such as those induced by mutation. Here we explore the relation between folding plasticity and a gross, generic feature of the native geometry, namely, the relative number of local and non-local native contacts. The results from our study, which is bas...

The thermal denaturation of adenosine deaminase (ADA) has been investigated in the presence of sodium n-dodecyl sulphate (SDS) over the temperature range of (293-363K) in 2.5 mM phosphate buffer, pH 6.4 by temperature scanning spectroscopy. The interaction of SDS caused the folding of adenosine deaminanse resulting in a decrease of TH (temperature of minimum solubility), TS<...

The relationship between protein synthesis, folding, and disulfide formation within the endoplasmic reticulum (ER) is poorly understood. Previous studies have suggested that pre-existing disulfide links are absolutely required to allow protein folding and, conversely, that protein folding occurs prior to disulfide formation. To address the question of what happens first within the ER, that is, ...

Folding of hydrophobic polypeptides into unique three-dimensional structures in a membrane is investigated by Monte Carlo simulations using the bond fluctuation model. Its ground state structure can be a helix or a double helix depending on the competition of hydrogen bonding and backbone bending energies. The folding pathway of hydrophobic polypeptides in a nonpolar environment is found to fav...

Protein folding is a diffusional process, and the speed of folding is controlled by the frictional forces that act on the polypeptide chain. Several previous studies have suggested that the bulk viscosity of the solvent is the only important source of friction in folding reactions. By contrast, our studies of the folding dynamics of the Tryptophan Cage, a small, ultrafast-folding protein, show ...

We studied the role of mitochondrial cyclophilin 20 (CyP20), a peptidyl-prolyl cis-trans isomerase, in preprotein translocation across the mitochondrial membranes and protein folding inside the organelle. The inhibitory drug cyclosporin A did not impair membrane translocation of preproteins, but it delayed the folding of an imported protein in wild-type mitochondria. Similarly, Neurospora crass...

Background: Group I introns are valuable for studying RNA folding and chaperone proteins. Results: A catalytic activity assay was developed and used to demonstrate two prominent phases for Azoarcus ribozyme folding. The slow phase displays hallmarks of a misfolded intermediate. Conclusion: This RNA accumulates a misfolded intermediate and interacts productively with RNA chaperones. Significance...

The protein folding is regarded as a quantum transition between torsion states on polypeptide chain. The deduction of the folding rate formula in our previous studies is reviewed. The rate formula is generalized to the case of frequency variation in folding. Then the following problems about the application of the rate theory are discussed: 1) The unified theory on the two-state and multi-state...

The relative folding rates of simple, single-domain proteins, proteins whose folding energy landscapes are smooth, are highly dispersed and strongly correlated with native-state topology. In contrast, the relative folding rates of small, Gō-potential lattice polymers, which also exhibit smooth energy landscapes, are poorly dispersed and insignificantly correlated with native-state topology. Her...