Insect flight muscle (IFM) from Lethocerus indicus is an asynchronous muscle which can keep on oscillating after a neural stimulation, as long... Show moreInsect flight muscle (IFM) from Lethocerus indicus is an asynchronous muscle which can keep on oscillating after a neural stimulation, as long as the load is mechanically-resonant. It has high degree of structural order as well. These characteristics make it an ideal material to study the structure of IFM in vitro. In this research, the structure of IFM from Lethocerus indicus was studied using X-ray diffraction. Multiple isomorphous replacement (MIR) using heavy atoms to alter the structure of biological macromolecules was used in an attempt to solve the well-known phase problem of crystallography. MIR is less commonly used in non-crystalline systems. Here we showed that, by labeling with two heavy atoms, potassium tetrachloroaurate (III) (KAuCl4) and p-Chloromercuribenzoic acid (PCMB), the diffraction patterns from IFM samples changed, in particular the intensities of reflections on the meridian. The positions and intensities of every layer line on the meridian before and after labeling were compared, and the best conditions for the two heavy atoms to use for labeling were discussed. These results indicate that this approach may be a feasible way of determining the electron density in this material with further development. M.S. in Biology, May 2012 Show less
