The effects of mildly acidic conditions on the free energy of unfolding (DeltaG(u)(buff)) of the pore-forming alpha-hemolysin (alphaHL) from Staphylococcus aureus were assessed between pH 5.0 and 7.5 by measuring intrinsic tryptophan fluorescence, circular dichroism and elution time in size exclusion chromatography during urea denaturation. Decreasing the pH from 7.0 to 5.0 reduced the calculat...

For decades, it has been known that the rate of postmortem glycolysis is variable in pig muscle (Briskey, et al., 1966). Elevated hydrogen ion concentrations (low pH) result from anaerobic glycolysis. Low pH, combined with high muscle temperature during the early postmortem period, causes denaturation and reduced solubility of sarcoplasmic proteins (Sayre and Briskey, 1963; Scopes, 1964; Joo et...

Many of the stability characteristics of horse ferrihemoglobin (Hb+) in acid solutions, such as pH dependence and susceptibility to stabilization by iron ligands, are shared by human ferrihemoglobin, but striking differences between the two proteins exist. The most noticeable is the much greater rate of denaturation of the human protein at all pH values. Other differences include a shift to hig...

the interaction between nano-sio2 and lysozyme was investigated by the method of uv-visible  detection and fluorescence spectroscopic techniques. the thermal denaturation of lysozyme has been investigated in the presence and absence of nano-sio2 over the temperature range (293-373) k in different buffers and ph values, using temperature scanning spectroscopy. the presence of nano-sio2 caused th...

We have used UV resonance Raman spectroscopy to study the acid denaturation of horse heart aquometmyoglobin (Mb) between pH 7.5 and 1.5. Raman spectra excited at 206.5 nm are dominated by amide vibrations, which are analyzed by using a new methodology to quantitatively determine the Mb secondary structure. In contrast, the 229-nm Raman spectra are dominated by the Tyr and Trp Raman bands, which...

The pH-dependent transitions and the thermal unfolding of defatted human serum albumin in 0.2 M KC1 as followed by polarimetry at 233 nm are found to be independent processes. The apparent net loss of structure (01 helix) in the unfolding between pH ‘7 and 9 is 2.5%, in the N-F transformation it is 8% and in the acid expansion 1%. The two last mentioned transitions seem to be independent of eac...

Botulinum Neurotoxin (BoNT) produced by the bacterium Clostridium botulinum as a complex with NAPs causes botulism. It has been known that the NAPs protect the toxin from both extremes of pHs and proteases of the GI tract. In an attempt to emulate the physiological conditions encountered by the toxin, we examined BoNT/A, BoNT/A complex, and NAPs under different pH conditions and monitored their...

Amaranth protein isolate (API) ultrathin structures have been developed using the electrospinning technique. The effects of pH, type of solvent and surfactant addition on the spinnability, morphology and molecular organization of the obtained structures have been studied. Regarding the effect of pH on API electrospinning, capsule morphologies were only obtained at extreme pH values (i.e. pH 2 a...

The pH-dependent transitions and the thermal unfolding of defatted human serum albumin in 0.2 M KC1 as followed by polarimetry at 233 nm are found to be independent processes. The apparent net loss of structure (01 helix) in the unfolding between pH ‘7 and 9 is 2.5%, in the N-F transformation it is 8% and in the acid expansion 1%. The two last mentioned transitions seem to be independent of eac...