Size and Structure of Cytochrome-c bound to Gold nano-clusters: Effect of Ethanol

Abstract

Size and structure of cytochrome c (Cyt C) bound to gold nano-clusters (AuNC) were studied using fluorescence correlation spectroscopy (FCS) and circular dichroism (CD) spectroscopy. The CD spectra of Cyt C indicate that the ellipticity is almost completely lost on binding to AuNC which indicates unfolding. Addition of ethanol causes partial restoration of ellipticity and hence, structure of Cyt C. FCS data indicate that size (hydrodynamic radius, r H) of free Cyt C is 17 Å which increases to 24 Å on binding to AuNC. This too suggests unfolding of Cyt C upon binding to AuNCs. Both the size and conformational relaxation time of Cyt C bound to AuNC vary non-monotonically with increase in ethanol content.

Antigen-Adjuvant Interactions in Vaccines by Taylor Dispersion Analysis: Size Characterization and Binding Parameters

“…An hydrodymanic radius (R h ) of 23 ± 3 nm was determined for SPA09, 1.8 ± 0.1 nm for Cyt C, 2.1 ± 0.1 nm for RNase A and 3.5 ± 0.2 nm for PrSA (see Table 1), according to equations (S-3 and S-4). The results obtained for the model proteins Cyt C and RNase A are consistent with the values found in literature 40,41 . In a second set of experiments, Cyt C-SPA09 interactions were studied by injecting a mixture of 0.8 g/L Cyt C and 1 g/L SPA09 in 20 mM TRIS, 148 mM NaCl, pH 7.4 (thereafter called TRIS buffer).…”

“…The results obtained for the model proteins Cyt C and RNase A are consistent with the values found in the literature. 40,41 In a second set of experiments, Cyt C-SPA09 interactions were studied by injecting a mixture of 0.8 g/L Cyt C and 1 g/L SPA09 in 20 mM TRIS, 148 mM NaCl, pH 7.4 (thereafter called TRIS buffer). The signal obtained by the first derivative of the elution profile was not symmetrical, as seen in Figure 1A.…”

Conducting and Characterizing Femto Flow Electrospray Ionization

“…Plug in this and the 400 fA ionization current, 16 equation ( 3) returns a size of >21 nm for the fA ESI. Considering that the hydrodynamic radius in cyt c is 1.7 ±0.2 nm, 22,23 the calculated droplet size confirms the generation of charged droplets in fA ESI and rules out the possible hypothesis 24 of direct ion emission 25 from a nanoscale meniscus in the emitter tip, which would be similar to the electrohydrodynamic atomization 26 in vacuum.…”

Conducting and characterizing femto flow electrospray ionization

“…Using these values and the 400 fA ionization current, 16 eqn (3) returns a droplet size larger than 34–87 nm for the fA ESI. Considering that the hydrodynamic radius in cyt c is 1.7 ± 0.2 nm, 24,25 these sizes suggest the spraying of charged droplets in fA ESI. The postulated direct ion emission 26 from a nanoscale meniscus 27 is possible but it alone would not produce the estimated flow rate.…”