Stabilization of Folding Intermediate States from Alkaline Induced Unfolded State of Bovine Serum Fetuin in Trifluoroethanol and Acetonitrile

Abstract

The conformation of bovine serum fetuin (BSF) was examined over the pH 7.0-12.9 regions by circular dichroism, intrinsic fluorescence and ANS binding. We observed that at higher pH, BSF exists in alkaline unfolded state. Our results provided evidence that correlates simultaneous formation of secondary structure followed by accumulation of hydrophobic clusters.

The thermal behavior of collagen in solution: Effect of glycerol and 2-propanol

“…Furthermore, the stability of bovine serum fetuin [9], bovine serum albumin [10], lectin [11,12], and hen egg white lysozyme [13] in alcohols including fluoroalcohol, polyethylene glycol and tertiary butanol were studied. Alcohols were also used for studying the thermal stability of collagen in solutions [14][15][16].…”

Trifluoroethanol stabilizes the molten globule state and induces non-amyloidic turbidity in stem bromelain near its isoelectric point

“…However, the protein conformation can be influenced by many factors including, but not limited to, solvents, mechanical forces, chemical denaturants, and pH. Extremes of pH can induce pre-molten globule states, molten globules (MGs), partially folded intermediates, and aggregates of native proteins [2][3][4][5][6][7][8]. Protein folding at alkaline pH has not been extensively characterized, and even less studied is the effect of fluoroalcohols on these alkali-induced states [8].…”

“…Binary mixtures of water with alcohols such as methanol, ethanol, or 2,2,2-trifluoroethanol (TFE) denature the tertiary and quaternary structures of proteins while enhancing their helicity [6][7][8][9][10][11][12]. Several alcohols weaken non-local hydrophobic interactions while promoting local polar interactions (e.g., hydrogen bonds), stabilizing the extended helical rods in which hydrophobic side chains are exposed while polar amide groups are shielded from the solvent [13][14][15][16].…”

“…Comparing these structural intermediates of a protein could provide clues to the nature of protein folding [23,27]. Although extremely high pH conditions are not usually relevant physiologically, moderate alkaline conditions (e.g., pH [7][8][9][10] are often encountered by proteins in physiological settings and can induce stable folding intermediates such as the MG. Stem bromelain (3.4.22.32) (SBM), a widely accepted phytotherapeutic drug obtained from Ananas comosus [28], is known to be anti-edematous, anti-inflammatory, and anti-metastasic, and it enhances the absorption of drugs, particularly antibiotics [29][30][31].…”