Inactivation of Aeromonas Hydrophila Metallo-Beta-Lactamase by Cephamycins and Moxalactam

Incubation of moxalactam and cefoxitin with the Aeromonas hydrophila metallo-beta-lactamase CphA leads to enzyme-catalyzed hydrolysis of both compounds and to irreversible inactivation of the enzyme by the reaction products. As shown by electrospray mass spectrometry, the inactivation of CphA by cefoxitin and moxalactam is accompanied by the formation of stable adducts with mass increases of 445 and 111 Da, respectively. The single thiol group of the inactivated enzyme is no longer titrable, and dithiothreitol treatment of the complexes partially restores the catalytic activity. The mechanism of inactivation by moxalactam was studied in detail. Hydrolysis of moxalactam is followed by elimination of the 3' leaving group (5-mercapto-1-methyltetrazole), which forms a disulfide bond with the cysteine residue of CphA located in the active site. Interestingly, this reaction is catalyzed by cacodylate

A 167-processor 65 nm computational platform with per-processor dynamic supply voltage and dynamic clock frequency scaling

A 167-processor 65 nm computational platform well suited for DSP, communication, and multimedia workloads contains 164 programmable processors with dynamic supply voltage and dynamic clock frequency circuits, three algorithm-specific processors, and three 16 KB shared memories, all clocked by independent oscillators and connected by configurable long-distance-capable links

Macromolecules at surfaces: Research challenges and opportunities from tribology to biology

A comprehensive review of ongoing and recommended research directions concerning the structure, dynamics, and interfacial activity of synthetic and naturally occurring macromolecules at the solid-liquid interface is presented. Many new developments stem from the ability to target new size regimes of 1-100 nm. These rapid developments are reviewed critically with respect to chemical synthesis, processing, structural characterization, dynamic processes, and theoretical and computational analysis. The common problems shared by flat and particulate sur-faces are emphasized. A broad spectrum of material properties are discussed, from the control of interfacial friction between surfaces in moving contact, to the mechanical strength and durability of the interfaces in hybrid materials, to optical and electronic properties. Future-research opportunities are identified that involve (1) the emergence of nanoscale material properties, (2) polymer-assisted nanostructures, and (3) the crossroads between interfacial science and biological and bioinspired applications. (C) 2003 Wiley Periodicals, Inc