Detection of non-topological motifs in protein structures

We present an efficient technique for the comparison of proteinstructures. The algorithm uses a vector representation of thesecondary structure elements and searches for spatial configurationsof secondary structure elements in proteins. In such recurringprotein folds, the order of the secondary structure elementsin the protein chains is disregarded. The method is based onthe geometric hashing paradigm and implements approaches originatingin computer vision. It represents and matches the secondarystructure element vectors in a 3-D translation and rotationinvariant manner. The matching of a pair of proteins takes onaverage under 3 s on a Silicon Graphics Indigo2 workstation,allowing extensive all-against-all comparisons of the data setof non-redundant protein structures. Here we have carried outsuch a comparison for a data set of over 500 protein molecules.The detection of recurring topological and non-topological,secondary structure element order-independent protein foldsmay provide further insight into evolution. Moreover, as theserecurring folding units are likely to be conformationalHy favourable,the availability of a data set of such topological motifs canserve as a rich input for threading routines. Below, we describethis rapid technique and the results it has obtained. Whilesome of the obtained matches conserve the order of the secondarystructure elements, others are entirely order independent. Asan example, we focus on the results obtained for Che Y, a signaltransduction protein, and on the profilin-ß-actincomplex. The Che Y molecule is composed of a five-stranded,parallel ß-sheet flanked by five helices. Here weshow its similarity with the Escherichia coli elongation factor,with L-arabinose binding protein, with haloalkane dehalogenaseand with adenylate kinase. The profilin–ß-actincontains an antiparallel ß-pleated sheet with -helicaltermini. Its similarities to lipase, fructose disphosphataseand ß-lactamase are displayed.     

Novel Triclosan‐Bound Hybrid‐Silica Nanoparticles and their Enhanced Antimicrobial Properties

The design and synthesis of novel hybrid‐silica nanoparticles (NPs) containing the FDA‐approved antimicrobial triclosan (Irgasan) covalently linked within the inorganic matrix for its controlled, slow release upon interaction, is reported. The NPs are in the range of 130 ± 30 nm in diameter, with a smooth and spherical morphology. Characterization of the hybrid‐silica NPs containing triclosan, namely T‐SNPs, and their appropriate linkers is accomplished by microscopic and spectroscopic techniques. Preliminary antimicrobial activity is studied through bacterial‐growth experiments. The T‐SNPs are found to be superior in killing bacteria, as compared with the free biocide.     

Calculating the process of removing bond from insulator castings

Glass and Ceramics -