An Effector of Hemoglobin Structure: The Guanosine 3', 5'-Triphosphate

Abstract

Abstract. The effect of guanosine 3', 5'-triphosphate (GTP) on the hemoglobin structure was studied by UV-visible, fluorescence and circular dichroism (CD) spectroscopies, and cyclic voltammetry. UV-visible absorption spectra showed an increase in absorbance in the regions of 420 nm and 280 nm. Fluorescence spectra showed that the Trp fluorescence intensity increased upon excitation at 280 nm, when guanosine 3', 5'-triphosphate concentration was increased in hemoglobin solution. Along with the increased fluorescence intensity, a slightly shift of λ max was also observed toward the higher wavelengths. CD spectral analysis demonstrated a significant decrease in negative ellipsity in the region of 205-235 nm. After adding guanosine 3', 5'-triphosphate to the hemoglobin solution α-helix structure decreases by 20 % while β-sheet conformation increases by 9 %. The effects of GTP on hemoglobin resulted in a 61 mV shift in the cathodic and 40 mV for anodic peak of hemoglobin in the CD. Our data showed the change of secondary and tertiary structure of hemoglobin in the presence of guanosine 3', 5 '-triphosphate. (doi: 10.5562/cca1955)

The effect of the gene carrier material polyethyleneimine on the structure and function of human red blood cells in vitro

“…Altogether, the interaction between Hb and the BPEIs causes the changes in the protein structure and decreases the absorption of Trp residues/heme groups. 15 As reported, the UV-vis absorption intensity of the Soret band is decreased by interacting with silver nanoparticles, 16 but is increased by interacting with guanosine 3 0 ,5 0 -triphosphate. 15 In contrast, while BPEI is toxic at high concentration, even a polymeric hydrogel of theoretical innite molecular weight yet of basically neutral chains does not signicantly alter the spatial structure of Hb.…”

“…Generally, Trp residues in a hydrophobic microenvironment exhibit maximum emission at lower wavelengths as compared to a hydrophilic-or exposed-environment. 15 According to this, Hb and the BPEIs may have some interaction, improving the non-polarity of the microenvironment around Trp residues and increasing the uorescence emission intensity of Trp residues. The interaction should mainly be mediated by their electrostatic attraction, in view of the overall negative nature of the physiological environment of bovine Hb with an isoelectric point at pH 7.1.…”

“…The interaction should mainly be mediated by their electrostatic attraction, in view of the overall negative nature of the physiological environment of bovine Hb with an isoelectric point at pH 7.1. 19 The uorescence enhancement of Hb was also reported by interacting with guanosine 3 0 ,5 0triphosphate, 15 while the uorescence quenching of Hb was reported by interacting with silver nanoparticles. 16 In contrast, the uorescence quenching was reported for serum albumin by other biopolymers such as PAMAM, 20 cholesterol-modied O-carboxymethyl chitosan, 21 poly[9,9-bis(3 0 -butyrate)uoren-2,7-yl] sodium, 22 etc.…”