Fluorinated alcohol, the third group of cosolvents that stabilize the molten‐globule state relative to a highly denatured state of cytochrome c

Abstract

The effects of 1,1,1,3,3,3-hexafluoro-isopropanol~HFIP! on the conformation of cytochrome c~cyt c! at pH 1.9 were studied using a combination of spectroscopic and physical methods. Analysis varying the HFIP concentration showed that a compact denatured conformation~M HF ! accumulates in a low concentration range of HFIP in the middle of structural transition from the highly unstructured acid-denatured state to the highly helical alcohol-denatured state of cyt c. This contrasts clearly with the effect of isopropanol~IP!, in which no compact conformation accompanied with the transition. Analysis varying concentrations of HFIP and NaCl concurrently showed that the M HF state of cyt c is essentially identical to the salt-induced molten-globule~M G ! state, and the M G state in the presence of salt was also stabilized by a low concentration of HFIP. Furthermore, 2,2,2-trifluoroethanol stabilized M HF similarly to HFIP, supporting the proposition that the specific effect observed for HFIP is caused by fluorination of alcohol. The mechanism stabilizing compact conformation by HFIP remains unclear, but is probably distinct from that of salts and polyols, which are also known to stabilize the M G -like state.

Cooperative α-helix formation of β-lactoglobulin induced by sodium n-alkyl sulfates

“…The intrinsic viscosity and Stokes radius, R s [74][75][76][77], are crucial measurements of the incompactness of intermediate forms than to native state. The R s values in Table 1 show the most compact state is the native form.…”

How methyl cyanide induces aggregation in all-alpha proteins: A case study in four albumins

“…On the other hand, MeCN induces or enhances beta sheet in some proteins [18]. In alcohols and other cosolvents, the non-polar groups of proteins tend to get interact with hydrophobic regions of the cosolvents, thus decreasing the environmental polarity around the polypeptide which in turn favors the formation of hydrogen bonds resulting in helical structure [19,20]. In contrast, MeCN induces beta sheet, due to its higher polarity than alcohols in water, which provides a favorable environment for the formation of intermolecular beta sheets [21][22][23][24].…”

Charge neutralization as the major factor for the assembly of nucleocapsid-like particles from C-terminal truncated hepatitis C virus core protein

“…Alcohols are known to modulate the interactions of the polypeptide chain, and trifluorethanol (TFE) has been used to induce the formation of helical structure in protein fragments and peptides (Dyson & Wright, 1993; Hamada et al, 2000) and in many other instances is known to transform proteins into molten globule-like intermediates (Konno, Iwashita & Nagayama, 2000) and sometimes to stabilize intermediate structures (Luo & Baldwin, 1998). To investigate the effects of alcohols on the C124 structure, the samples were incubated in the presence of 10–50% of either butanol or its fluorinated derivative, TFE.…”