7,141 research outputs found
The minimal structure containing the band 3 anion transport site. A 35Cl NMR study
35Cl NMR, which enables observation of chloride binding to the anion transport site on band 3, is used in the present study to determine the minimal structure containing the intact transport site. Removal of cytoskeletal and other nonintegral membrane proteins, or removal of the 40-kDa cytoskeletal domain of band 3, each leave the transport site intact. Similarly, cleavage of the 52-kDa transport domain into 17- and 35-kDa fragments by chymotrypsin leaves the transport site intact. Extensive proteolysis by papain reduces the integral red cell membrane proteins to their transmembrane segments. Papain treatment removes approximately 60% of the extramembrane portion of the transport domain and produces small fragments primarily in the range 3-7 kDa, with 5 kDa being most predominant. Papain treatment damages, but does not destroy, chloride binding to the transport site; thus, the minimal structure containing the transport site is composed solely of transmembrane segments. In short, the results are completely consistent with a picture in which the transport site is buried in the membrane where it is protected from proteolysis; the transmembrane segments that surround the transport site are held together by strong attractive forces within the bilayer; and the transport site is accessed by solution chloride via an anion channel leading from the transport site to the solution
Chloride binding to the anion transport binding sites of band 3. A 35Cl NMR study
Band 3 is an integral membrane protein that exchanges anions across the red cell membrane. Due to the abundance and the high turnover rate of the band 3 transport unit, the band 3 system is the most heavily used ion-transport system in a typical vertebrate organism. Here we show that 35Cl NMR enables direct and specific observation of substrate Cl- binding to band 3 transport sites, which are identified by a variety of criteria: (a) the sites are inhibited by 4,4'- dinitrostilbene -2,2'- disulfonate, which is known to inhibit competitively Cl- binding to band 3 transport sites; (b) the sites have affinities for 4,4'- dinitrostilbene -2,2'-disulfonate and Cl- that are quantitatively similar to the known affinities of band 3 transport sites for these anions; and (c) the sites have relative affinities for Cl-, HCO-3, F-, and I- that are quantitatively similar to the known relative affinities of band 3 transport sites for these anions. The 35Cl NMR assay also reveals a class of low affinity Cl- binding sites (KD much greater than 0.5 M) that are not affected by 4,4'- dinitrostilbene -2,2'- disulfonate. These low affinity sites may be responsible for the inhibition of band 3 catalyzed anion exchange that has been previously observed at high [Cl-]. In the following paper the 35Cl NMR assay is used to resolve the band 3 transport sites on opposite sides of the membrane, thereby enabling direct observation of the transmembrane recruitment of transport sites
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Network and Algebraic Topology of Influenza Evolution
Evolution is a force that has molded human existence since its divergence from chimpanzees about 5.4 million years ago. In that same amount of time, an influenza virus, which replicates every six hours, would have undergone an equivalent number of generations over only a hundred years. The fast replication times of influenza, coupled with its high mutation rate, make the virus a perfect model to study real-time evolution at a mega-Darwin scale, more than a million times faster than human evolution. While recent developments in high-throughput sequencing provide an optimal opportunity to dissect their genetic evolution, a concurrent growth in computational tools is necessary to analyze the large influx of complex genomic data. In my thesis, I present novel computational methods to examine different aspects of influenza evolution.
I first focus on seasonal influenza, particularly the problems that hamper public health initiatives to combat the virus. I introduce two new approaches: 1. The q2-coefficient, a method of quantifying pathogen surveillance, and 2. FluGraph, a technique that employs network topology to track the spread of seasonal influenza around the world.
The second chapter of my thesis examines how mutations and reassortment combine to alter the course of influenza evolution towards pandemic formation. I highlight inherent deficiencies in the current phylogenetic paradigm for analyzing evolution and offer a novel methodology based on algebraic topology that comprehensively reconstructs both vertical and horizontal evolutionary events. I apply this method to viruses, with emphasis on influenza, but foresee broader application to cancer cells, bacteria, eukaryotes, and other taxa
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Real-Time Value Chain Management
Value creation in the digital economy of the 21st century is characterized by the instantaneous processing and coordination of value chain activities across extended enterprises. Value chain management has evolved from automation and integration to the optimization of the entire value chain in real-time. This paper examines the real-time characteristics for each of the activities in the demand and supply value chains. A model is presented for real-time value chain management enabled by technologies in e-business, knowledge management and business intelligence
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Big Data Customer Knowledge Management
Knowledge management (KM) and customer relationship management (CRM) are dominant strategies for value creation for businesses in the new economy. Customer knowledge management (CKM) results in the merging of KM and CRM, where the knowledge management process is applied to customer knowledge, and customer knowledge is applied to customer relationship management operations. With the emergence of big data as the latest phase in the evolution of technology in business, CKM strategies need to be adjusted to meet the new challenges, changing from an internal organizational focus to new external channels such as social media and machine communications. This paper explores the concept of big data customer knowledge management. It presents an architecture that integrates CRM operations and KM processes with big data technologies that include NoSQL databases, Hadoop Distributed File System, MapReduce, and platforms for social media and machine-to-machine communications
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The Anatomy of Real-Time CRM
In the digital economy of the 21st century, the focus of production efficiency and product differentiation is shifted to value creation and relationship management. Customer relationship management is a critical business strategy in gaining competitive advantages. The ubiquity of the Internet has changed the way businesses are conducted. Real-time CRM is becoming increasingly significant to enable the agility of businesses to provide quick, accurate and complete responses to customer needs. This paper examines the structural makeup of real-time CRM that consists of e-business enabled CRM (ECRM), knowledge enabled CRM (KCRM) and business intelligence enabled CRM (ICRM). An architecture is developed for real-time CRM utilizing the components of e-business, knowledge-based systems, virtual data warehousing and real-time analytics
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E-Business Enabled ERP II Architecture
The economy of the 21st century that suceeds the service and production economies has significant impact to business strategies. In this new economy, businesses compete as integral parts of global value network fueled by the Internet and Globalization. Critical to the competitive strategy are efficient real-time operations and the exploitation of relationship and knowledge assets across the value network
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