This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Beam time is requested for studying the structures of Cowpea mosaic virus (CPMV) crystallized in hexagonal and orthorhombic cells by X-ray crystallography. Our goal is to understand the packing and structures of CPMV in large unit cells for the synthesis of porous metallic blocks with photonic properties. We have previously shown that the cubic crystals of CPMV, with unit cell dimensions of 30nm, could be employed as scaffolds for the synthesis of porous metallic blocks by infiltration of the solvent channels with elemental Pd and Pt. The materials produced by the chemical methods of electroless plating are with highly regular repeats of cavity. Theoretical calculations show that these metallized crystals are applicable as photonic materials with a band gap of 35nm. Up to date, however, we have not been able to find a suitable X-ray source to experimentally test the theories. Great progress can be made in this fusion of biology and nano-technology if crystals of larger unit cells can be employed. To this end, CPMV are crystallized in two other forms with much larger unit cells. The cell dimensions of hexagonal form are of 450, 450, 1035 A and that of an orthorhombic form are of 280, 280, and 812 A. Both of these crystals diffracted X-ray to beyond 3A. It was determined that the space group of hexagonal crystal was P6122, but not enough data were collected for the structural determination. Some data for the orthorhombic crystal were also collected in 14-BMC but more data were required to determine the space group and the structure. We would like to obtain full data sets from the hexagonal and orthorhombic crystals to investigate the virus particle packing and to determine the structures. These crystallographic information will be the basis for the calculation of the photonic properties and the subsequent synthesis of the photonic band gap materials using the virus crystals as the scaffolds.
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