Structure And Function Of Theoretical Studies On Vitreoscilla Hemoglobin D-region

Oxygen transport by hemoprotein is a widespread biological function which hasbeen recongnized in animals, plants, and microoriganisms. That the vitreoscillahemoglobin was found marked the beginning of the study of mircrobial hemoglobinsas an active area of inquiry. The report by Wakabaysh showed the amino acidsequence of VHb in1986, and first named vitreoscilla hemoglobin. With furtherresearch, people learned that the Vitreoscilla hemoglobin expression well inconditions of limited oxygen. Comparing with the hemoglobin of eukaryotic, Oxygendissociation rate of the vitreoscilla hemoglobin was higher. The efficient that VHbtransports oxygen to the host is widely applied to microbial metabolism and plantmetabolism. In process of microbial, the oxygen concentration is a key factor thatrestricts the efficiency of microbial growth. VHb carries oxygen to the host that cansolve the problem of oxygen supply. in process of microbial fermentation, such as E.coli, Streptomyces, Bacillus, and yeast engineered bacteria have importantapplications. As plant metabolism, the ability of effient delivery of oxygen canimprove the growth of submergence of crops and the plant charateristics.About thephysiological function of VHb, there are two mainstream interpretationhypothesis.one is the the hypothesis of diffusion. This hypothesis suggests that VHbtransports oxygen to the terminal oxidase. And Khosla and Bailey that found VHb istransported to the periplasmic space provided the hypothesis of diffusion. Another isthe hypothesis of redox condition that VHb affect the activity of intracellularredox-sensitive molecules in cytoplasmic, and Dikshit who confirmed that thebredthing efficiency can increase the yield of ATP provided the hypothesis of redoxcondition.In1997,Tarricone found the crystal structure of VHb. The structure of VHb conforms to the globin fold. VHb contains six α-helix, and comparing with theeukaryotic hemoglobin the D region of VHb is disordered. In2010,Zhao study foundthat VHb had two different forms that was the trend of cnoversion. In2002, Andreaobtained the structure of HMP.The HMP of globin protein wth the VHb homology is51%. The D region of HMP is α-helix structure.In2010, Mark S obtained thestructure of Cgb. The Cgb with the VHb homology is49%,But the D region of VHb isloop structure.This provides good templates for us to study VHb with moleculardynamics. We use two kinds of protein to build complete the structure of VHb andmolecular dynamics studys the stability of the two structures.We build two structure of D region with the double models. then we obtaintwo VHb of models with the energy balancing after the process of protein solvation,protein energy minimization, energy balance. Within50ns molecular dynamicssimulation, we analyse the structure of the RMSD, energy, RMSF, and radiu ofgyration. The RMSD and energy analysis show that two structure are stabilized in50ns. The D region of stability state is a short α-helix structure. The D regionstructure is between VhbA and VHbB structure. The RMSF shows that D region ofVHbB changes large floating. It is caused by forming a short α-helix structure. Theradiu of gyration shows two structures conform to the globin fold.