Purification, characterization and immunolocalization of fimbrial protein from Porphyromonas (bacteroides) gingivalis.

Rapid and reproducible method is described here for the purification of the 43 kDa fimbrial protein from P. gingivalis by preferential fractionation in the presence of 1% SDS and 0.2M of a bivalent cation at pH 6.5. Homogeneity of the purified 43 kDa was confirmed by SDS-PAGE and Western blot analysis using monoclonal and polyclonal antibodies raised against this protein. Amino acid composition and the amino acid sequence of the first 30 amino acid residues of the purified fimbriae are consistent with the composition and sequence predicted from the cloned gene of the fimbrial subunit. Circular dichroism spectra shows high levels of beta-sheet structure. The purified 43 kDa polymer shows fimbriae-like morphology under the electron microscope. Ultrastructural localization of the 43 kDa protein by the immunogold technique revealed specific labeling of the fimbriae with a diameter of approximately 3.5 to 5.0 nm. Localization of this protein suggest that the 43 kDa component is a fimbrial subunit.     

Phosphorylating-dephosphorylating enzymes of avian oviductal secretions

Avian oviductal fluids contain phosphorylating-dephosphorylating enzymes that might function in sperm-oocyte interactions. Phosphorprotein phosphatase and protein kinase have been purified 20-fold and 40-fold, respectively. The latter easily aggregates and is highly labile. Other properties are comparable to those of holoenzymes.     

Atom ordering in cuboctahedral Ni-Al nanoalloys

Energy calculations have been carried out on high-symmetry cuboctahedral Ni-Al nanoalloy clusters, of varying composition, with the interatomic interactions modelled by the Gupta many-body potential. Relaxations of cuboctahedral fragments cut from the bulk lattice of Ni₃Al, with 13-561 atoms, were undertaken, as were relaxations of high symmetry clusters with 55 and 147 atoms. The lowest energy isomers were found to be dominated by three factors: the tendency toward mixing due to the favourable energy of mixing, Δ_mixE; the size difference between nickel and aluminium; and the higher cohesive and surface energy of nickel compared to aluminium. The latter two factors favour Al-segregation to the surface. The most stable Ni:Al composition approaches 3:1 for larger clusters.