Detailed Structure–Function Correlations of Bacillus subtilis Acetolactate Synthase

Isobutanol is deemed to be a next‐generation biofuel and a renewable platform chemical. 1 Non‐natural biosynthetic pathways for isobutanol production have been implemented in cell‐based and in vitro systems with Bacillus subtilis acetolactate synthase (AlsS) as key biocatalyst. 2 – 6 AlsS catalyzes the condensation of two pyruvate molecules to acetolactate with thiamine diphosphate and Mg²⁺ as cofactors. AlsS also catalyzes the conversion of 2‐ketoisovalerate into isobutyraldehyde, the immediate precursor of isobutanol. Our phylogenetic analysis suggests that the ALS enzyme family forms a distinct subgroup of ThDP‐dependent enzymes. To unravel catalytically relevant structure‐function relationships, we solved the AlsS crystal structure at 2.3 Å in the presence of ThDP, Mg²⁺ and in a transition state with a 2‐lactyl moiety bound to ThDP. We supplemented our structural data by point mutations in the active site to identify catalytically important residues.     

相思木浆用于文化用纸生产时的滤水性能和留着性能

对来自印度尼西亚的相思木 (Acacia)浆与混合阔叶木浆和来自北欧的桦木浆进行对比分析 ,以期获得用于文化用纸生产时湿部的潜在滤水、留着性能及相关的手抄片性能 ,这些性能比较均基于恒定的抗张强度水平。相思木浆被证明拥有在文化用纸生产中至关重要的光散射能力、湿部成形和填料留着能力方面的优越性。需要改进的地方是 :它的滤水速率和湿纸幅强度较低 ,这些将是现代高速纸机湿部的瓶颈所在。相比之下 ,桦木浆具有较快的滤水速率和较高的湿部固含量 ,但其留着性能还有待改进     

Structure‐Based Mechanism of Oleate Hydratase from Elizabethkingia meningoseptica

Hydratases provide access to secondary and tertiary alcohols by regio‐ and/or stereospecifically adding water to carbon‐carbon double bonds. Thereby, hydroxy groups are introduced without the need for costly cofactor recycling, and that makes this approach highly interesting on an industrial scale. Here we present the first crystal structure of a recombinant oleate hydratase originating from Elizabethkingia meningoseptica in the presence of flavin adenine dinucleotide (FAD). A structure‐based mutagenesis study targeting active site residues identified E122 and Y241 as crucial for the activation of a water molecule and for protonation of the double bond, respectively. Moreover, we also observed that two‐electron reduction of FAD results in a sevenfold increase in the substrate hydration rate. We propose the first reaction mechanism for this enzyme class that explains the requirement for the flavin cofactor and the involvement of conserved amino acid residues in this regio‐ and stereoselective hydration.     

Macrodiversity analysis of anM-ary noncoherent orthogonal DS/CDMA system on shadowed Rayleigh channels

DS/CDMA noncoherentM-ary orthogonal signaling is presented in a hexagonal cell with three and six corner-based antennas. Multipath Rayleigh channel with lognormal shadowing and perfect power control are assumed. The asynchronous case (uplink) is studied. Bit error rate analysis is carried out to investigate the benefits of combining theM-ary orthogonal signaling and macrodiversity techniques either with uncorrelated or correlated base stations. Comparative analysis between the one central antenna arrangement and the proposed one is presented. The results show that the combination ofM-ary signaling with multiple corner-based antennas improves system performance especially in terms of accommodating more users and supporting new services. The results also show that shadowing does not degrade system performance significantly.     

Using Singular Value Decomposition to Characterize Protein–Protein Interactions by In‐cell NMR Spectroscopy

Distinct differences between how model proteins interact in‐cell and in vitro suggest that the cytosol might have a profound effect in modulating protein–protein and/or protein–ligand interactions that are not observed in vitro. Analyses of in‐cell NMR spectra of target proteins interacting with physiological partners are further complicated by low signal‐to‐noise ratios, and the long overexpression times used in protein–protein interaction studies may lead to changes in the in‐cell spectra over the course of the experiment. To unambiguously resolve the principal binding mode between two interacting species against the dynamic cellular background, we analyzed in‐cell spectral data of a target protein over the time course of overexpression of its interacting partner by using single‐value decomposition (SVD). SVD differentiates between concentration‐dependent and concentration‐independent events and identifies the principal binding mode between the two species. The analysis implicates a set of amino acids involved in the specific interaction that differs from previous NMR analyses but is in good agreement with crystallographic data.     

Hardware assisted watermarking for multimedia

Digital media offer several distinct advantages over analog media, such as high quality, ease of editing, and ease of processing operations such as compression and high fidelity copying. Digital data is commonly available through digital TV broadcast, CD, DVD, and computing devices such as personal computers. The ease by which a digital media object can be duplicated and distributed has led to the need for effective digital rights management tools. Digital watermarking is one such tool. Watermarking is the process of embedding extra data called a watermark into a multimedia object, like image, audio, or video, such that the watermark can later be detected or extracted in order to make an assertion regarding the object. During the last decade, numerous software based watermarking schemes have appeared in the literature and watermarking research has attained a certain degree of maturity. But hardware based watermarking systems have evolved more recently only and they are still at their infancy. The goal of hardware assisted watermarking is to achieve low power usage, real-time performance, reliability, and ease of integration with existing consumer electronic devices. In this paper, we survey the hardware assisted solutions proposed in the literature for watermarking of multimedia objects. The survey is preceded by an introduction to the background issues involved in digital watermarking.     

Chemometric Characterization of Eight Monovarietal Algerian Virgin Olive Oils

Differences in triacylglycerol, fatty acid, squalene, and tocopherol compositions were demonstrated between 8 varieties of virgin olive oils (Aberkane, Aguenaou, Aharoun, Aimel, Bouchouk Guergour, Bouichret, Chemlal, and Sigoise) from Petite Kabylie area, north eastern Algeria. Fatty acid and triacylglycerol morphotypes characterized each variety. A principal component analysis, based on triacylglycerol, fatty acid, and squalene compositions, differentiates between varieties. Minor fatty acids and squalene, usually not taken into account individually in authentication studies, are strongly involved in this differentiation, whereas the discriminant power of tocopherols is weak. Soft Independent Modeling of Class Analogy classification using chemical compositions as variables showed a high potential to authenticate the varietal origin of Algerian virgin olive oils.     

An object design framework for structural engineering

Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system.