Title
Differential sensitivity of Chironomus and human hemoglobin to gamma radiation
Author
Pallavi S. Gaikwad, Lata Panicker, Madhura Mohole, Sangeeta Sawant, Rita Mukhopadhyaya, Bimalendu B. Nath
Year
2016
Journal
Biochemical and Biophysical Research Communications
Abstract
Chironomus ramosus is known to tolerate high doses of gamma radiation exposure. Larvae of this insect possess more than 95% of hemoglobin (Hb) in its circulatory hemolymph. This is a comparative study to see effect of gamma radiation on Hb ofChironomus and humans, two evolutionarily diverse organisms one having extracellular and the other intracellular Hb respectively. Stability and integrity of Chironomus and human Hb to gamma radiation was compared using biophysical techniques like Dynamic Light Scattering (DLS), UV-visible spectroscopy, fluorescence spectrometry and CD spectroscopy after exposure of whole larvae, larval hemolymph, human peripheral blood, purified Chironomus and human Hb. Sequence- and structure-based bioinformatics methods were used to analyze the sequence and structural similarities or differences in the heme pockets of respective Hbs. Resistivity of Chironomus Hb to gamma radiation is remarkably higher than human Hb. Human Hb exhibited loss of heme iron at a relatively low dose of gamma radiation exposure as compared to ChironomusHb. Unlike human Hb, the heme pocket of Chironomus Hb is rich in aromatic amino acids. Higher hydophobicity around heme pocket confers stability of Chironomus Hb compared to human Hb. Previously reported gamma radiation tolerance of Chironomuscan be largely attributed to its evolutionarily ancient form of extracellular Hb as evident from the present study.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Protein folding, Biochemistry