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Catalytic Event (catalytic + event)
Selected AbstractsMark as a Roman Document from the Year 69: Testing Martin Hengel's ThesisJOURNAL OF RELIGIOUS HISTORY, Issue 3 2004Ivan Head This paper explores Martin Hengel's thesis that the Gospel of Mark was written in Rome in the year 69. Hengel was convinced that more should be made of the Year of Four Emperors, a period of civic chaos and warfare that ensued on the death of Nero. The paper analyses the role of the emperor as a potent force in the religious, civic, political, and military unity that is Rome and her gods; the all-pervasive Jerusalem Temple; and Josephus's return to Rome in 71 and the publication of The Jewish War. The paper shows that these themes overlap with this Gospel and are at least consistently supportive of the claim that Rome is the place of composition. The paper refers positively to a recent publication by Brian Incigneri that stresses the critical role of the Triumph of Vespasian and Titus in 71 as the catalytic event for Mark. [source] Rail Safety: Targeting Oversight and Assessing ResultsPUBLIC ADMINISTRATION REVIEW, Issue 1 2008Jeremy F. Plant Rail safety has emerged as a significant issue in the past two years as a result of two major factors: a statistical lack of improvement in rail safety in the past decade, and a catalytic event in the form of a major derailment involving loss of life at Graniteville, South Carolina, in January 2005. The convergence of long-term leveling of rail safety indicators and the shock of a major rail accident prompted the Senate Appropriations Committee to ask the Government Accountability Office to assess the oversight role of the Federal Railroad Administration, the modal agency of the U.S. Department of Transportation charged with overseeing rail safety. The report is a reminder of the continuing importance of regulatory activities and the general movement in federal management toward greater use of data and performance measures since the Government Performance and Results Act of 1993. [source] The atomic resolution structure of human aldose reductase reveals that rearrangement of a bound ligand allows the opening of the safety-belt loopACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2007Marianna Biadene The crystal structure of human aldose reductase in complex with citrate has been determined to a resolution of 0.82,Å. The difference electron density for H atoms unequivocally shows that the cofactor is in the oxidized state corresponding to the situation after the catalytic event has occurred. A citrate molecule bound to the active site has been modelled in two different conformations. These two conformations correlate with a fully closed and a partially open conformation of the so-called safety-belt loop (Gly213,Ser226). The open conformation is observed for the first time with the cofactor bound to the protein and may be related to the initial phase of the opening of the safety belt. The structure suggests that after the catalytic event, a rearrangement of a bound ligand can trigger the opening of the safety-belt loop, thus initiating the release of the oxidized cofactor. [source] DNA topology and topoisomerasesBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 1 2009Teaching a "knotty" subject Abstract DNA is essentially an extremely long double-stranded rope in which the two strands are wound about one another. As a result, topological properties of the genetic material, including DNA underwinding and overwinding, knotting, and tangling profoundly influence virtually every major nucleic acid process. Despite the importance of DNA topology, it is a conceptionally difficult subject to teach because it requires students to visualize three-dimensional relationships. This article will familiarize the reader with the concept of DNA topology and offer practical approaches and demonstrations to teaching this "knotty" subject in the classroom. Furthermore, it will discuss topoisomerases, the enzymes that regulate the topological state of DNA in the cell. These ubiquitous enzymes perform a number of critical cellular functions by generating transient breaks in the double helix. During this catalytic event, topoisomerases maintain genomic stability by forming covalent phosphotyrosyl bonds between active site residues and the newly generated DNA termini. Topoisomerases are essential for cell survival. However, because they cleave the genetic material, these enzymes also have the potential to fragment the genome. This latter feature of topoisomerases is exploited by some of the most widely prescribed anticancer and antibacterial drugs currently in clinical use. Finally, in addition to curing cancer, topoisomerase action also has been linked to the induction of specific types of leukemia. [source] Probing nonnucleoside inhibitor-induced active-site distortion in HIV-1 reverse transcriptase by transient kinetic analysesPROTEIN SCIENCE, Issue 8 2007Qing Xia Abstract Nonnucleoside reverse transcriptase inhibitors (NNRTI) are a group of structurally diverse compounds that bind to a single site in HIV-1 reverse transcriptase (RT), termed the NNRTI-binding pocket (NNRTI-BP). NNRTI binding to RT induces conformational changes in the enzyme that affect key elements of the polymerase active site and also the association between the two protein subunits. To determine which conformational changes contribute to the mechanism of inhibition of HIV-1 reverse transcription, we used transient kinetic analyses to probe the catalytic events that occur directly at the enzyme's polymerase active site when the NNRTI-BP was occupied by nevirapine, efavirenz, or delavirdine. Our results demonstrate that all NNRTI,RT,template/primer (NNRTI,RT,T/P) complexes displayed a metal-dependent increase in dNTP binding affinity (Kd) and a metal-independent decrease in the maximum rate of dNTP incorporation (kpol). The magnitude of the decrease in kpol was dependent on the NNRTI used in the assay: Efavirenz caused the largest decrease followed by delavirdine and then nevirapine. Analyses that were designed to probe direct effects on phosphodiester bond formation suggested that the NNRTI mediate their effects on the chemistry step of the DNA polymerization reaction via an indirect manner. Because each of the NNRTI analyzed in this study exerted largely similar phenotypic effects on single nucleotide addition reactions, whereas each of them are known to exert differential effects on RT dimerization, we conclude that the NNRTI effects on subunit association do not directly contribute to the kinetic mechanism of inhibition of DNA polymerization. [source] | ||||||||||