Interaction of Myoglobin with Cationic and Nonionic Surfactant in Phosphate Buffer Media

Abstract

Interaction of myoglobin with cationic surfactants hexadecyltrimethylammonium bromide (HTAB), gemini surfactant 16-2-16 (dimethylene-1,2-bis(hexadecyldimethylammonium bromide)) and nonionic surfactant Mega 10 (N-decanoyl-N-methylglucamine) have been studied in phosphate buffer at pH 7.4 using surface tension, UV−visible, fluorescence, and circular dichroism spectroscopies and differential scanning calorimetry. With increasing concentration of HTAB, metal ion of the heme group changes its spin states; but in case of 16-2-16 and Mega 10, spin change does not occur. Fluorescence spectra clearly denote the unfolding process in HTAB media. With increasing HTAB concentration, α-helicity of myoglobin decreases with the appearance of β-sheet and random coil more rapidly than other two surfactants. Melting temperature of myoglobin is reduced drastically upon interaction with HTAB than their corresponding gemini and nonionic surfactants.

Mechanism and Dynamics of Long-Term Stability of Cytochrome c Conferred by Long-Chain Imidazolium Ionic Liquids at Low Concentration

“…The increase in the absorbance of the Soret peak indicates a transition toward nonpolar environment around the heme cleft as the hypochromic shifts in UV–vis spectra are observed due to the lowering in the energy of the π* orbital. The slight unfolding of h-cyt c has been reported with decreasing absorbance around 409 nm having peak at the same position . The inset in the Figure a,b shows the 695 nm peak (charge transfer band).…”

“…The slight unfolding of h-cyt c has been reported with decreasing absorbance around 409 nm having peak at the same position. 48 The inset in the Figure 3a,b shows the 695 nm peak (charge transfer band). This peak corresponds to the Met80− Fe interactions and measures local stability of protein (appears due to axial ligation of heme with Met80 that yields a sixcoordinated low-spin form); it is enhanced in the presence of ILs.…”

Influência do íon zinco na reatividade química da mioglobina

“…Em relação ao anel profirínico, a simetria da molécula e/ou dos orbitais moleculares é influenciado pela presença ou ausência de íons ferro, para os diferentes estados de oxidação do metal (MOREIRA, 2004). O tipo de transição eletrônica pode ser predito a partir da absortividade molar e da região espectral onde se observa as bandas (MONDAL et al, 2016). Os deslocamentos de bandas podem fornecer informações a respeito do ambiente químico, devido a interação do meio com os diferentes momentos de dipolo do estado excitado e do fundamental da porfirina (SHRIVER; ATKINS, 2009).…”

“…Nas porfirinas de base livre, o espectro de absorção eletrônica é observado com quatro bandas na região do visível, denominadas banda Q e máximo de absorção entre 500 nm e 700 nm (  10 4 L mol -1 cm -1 ). Uma outra banda de maior intensidade é observada em aproximadamente 400 nm (  10 5 L mol -1 cm -1 ), denominada banda Soret (ou banda B) (MONDAL et al, 2016).…”

“…A distribuição de tamanhos da proteína na presença de íons A diminuição de absorção na banda Soret (0,0) pode ser então atribuída à mudança de conformação da mioglobina, como reportado na literatura (AJLOO et al, 2002;MONDAL et al, 2016). Na investigação de Ajloo et al (2002) Tempo (min)…”