322,876 research outputs found
The elusive role played by the side chain of Lys249 of Plasmodium falciparum ferredoxin-NADP+ reductase in NADPH/NADH selectivity
No full textPlasmodium falciparum, the causative agent of tropical malaria, possesses plant-type ferredoxin-NADP+ reductase (PfFNR) and ferredoxin (PfFd), which have been proposed as targets for novel antimalarial drugs (1). The catalytic mechanism of PfFNR is under study in order to provide the bases for the design of effective enzyme inhibitors (2). Although PfFNR is quite specific for NADPH, no structural evidence was obtained for protein positive groups interacting with the 2’-phosphate of this substrate (3). We have found that change of Lys249 to Ala decreased the kcat/Km for NADPH by a factor of 10, without affecting the activity of the enzyme with NADH. In addition, PfFNR-K249A displayed an affinity for NADP+ 8-fold lower than those of the wild-type enzyme. We conclude that the side-chain of Lys249 actually interacts with the 2’-phosphate of NADPH during the catalytic cycle, and that it is part of a region flexible enough to adopt in the crystal form of the protein a conformation where such interaction is severed 1. Seeber, F., et al. (2005) Curr. Pharm. Des. 11, 3159-3172.
2. Crobu, D., et al. (2009) Biochemistry 48, 9525-9533.
3. Milani, M., et al. (2007) J. Mol. Biol. 367, 501-513
Studies of interaction between Rh(I) and Human Serum Albumin in a "nanostructured biocatalyst" active in the hydroformylation reaction
No full textThe interaction between Rh(CO)2(acac = acetylacetonate ion) and human serum albumin (HSA) in a hydrosoluble nanostructured
biocatalyst active in homogeneous hydroformylation was characterised by means of matrix assisted laser desorption ionization timeof-
flight mass spectrometry (MALDI-TOFMS), high performance liquid chromatography mass spectrometry (HPLC-MS) and scanning
electron microscopy (SEM). MALDI-TOFMS substantiates that the biocatalyst consists of a tetrameric structure of HSA that could
bind up to 89 RhðCOÞþ
2 units. A comparison between samples of pure HSA and the biocatalyst, both tryptic digested, showed a significant
change in the tertiary structure of the protein in the HSA/Rh adduct, probably ascribable to the interaction of Rh(I) ions with
sulphur atoms in the HSA moiety. SEM observations confirmed an evident denaturation of the protein and an outstanding correspondence
between the surface distribution of Rh and S atoms; this is indirect evidence that the metal ion interacts strongly mainly with the
sulphur atoms. Furthermore, an excellent agreement between calculated and measured (SEM) S/Rh elemental mean ratio was observed.
Finally, an electrostatic interaction between Rh(I) and sulphur atoms was ruled out by sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS–PAGE) findings
Preliminary characterization of the water soluble complex Rh/Human Serum Albumine, an active catalyst for olefin hydroformylation
No full textCharacterization of SDS PAGE separated M. agalactiae membrane antigens by mass spectrometry
No full text
A New Monopegylated Filgrastim Prepared By Transglutaminase Catalyzed Site Specific Reaction.
No full textDiffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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