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Micelle Maker : An Online Tool for Generating Equilibrated Micelles as Direct Input for Molecular Dynamics Simulations

Micelles play an important role in both experimental and computational studies of the effect of lipid interactions on biological systems. The spherical geometry and the dynamical behavior of micelles makes generating micelle structures for use in molecular simulations challenging. An easy tool for generating simulation-ready micelle models, covering a broad range of lipids, is highly desirable. He

Simulating the reactions of substituted pyridinio-N-phosphonates with pyridine as a model for biological phosphoryl transfer

Phosphoryl transfer reactions can proceed through several plausible mechanisms, and the potential for both solvent and substrate-assisted pathways (involving proton transfer to the phosphoryl oxygens) complicates both experimental and computational interpretations. To avoid this problem, we have used electronic structure calculations to probe the mechanisms of the reactions of pyridinio-N-phosphon

DNA Polymerase λ Active Site Favors a Mutagenic Mispair between the Enol Form of Deoxyguanosine Triphosphate Substrate and the Keto Form of Thymidine Template : A Free Energy Perturbation Study

Human DNA polymerase λ is an intermediate fidelity member of the X family, which plays a role in DNA repair. Recent X-ray diffraction structures of a ternary complex of a loop-deletion mutant of polymerase λ, a deoxyguanosine triphosphate analogue, and a gapped DNA show that guanine and thymine form a mutagenic mispair with an unexpected Watson-Crick-like geometry rather than a wobble geometry. He

De novo active sites for resurrected Precambrian enzymes

Protein engineering studies often suggest the emergence of completely new enzyme functionalities to be highly improbable. However, enzymes likely catalysed many different reactions already in the last universal common ancestor. Mechanisms for the emergence of completely new active sites must therefore either plausibly exist or at least have existed at the primordial protein stage. Here, we use res

Enzyme Architecture : Modeling the Operation of a Hydrophobic Clamp in Catalysis by Triosephosphate Isomerase

Triosephosphate isomerase (TIM) is a proficient catalyst of the reversible isomerization of dihydroxyacetone phosphate (DHAP) to d-glyceraldehyde phosphate (GAP), via general base catalysis by E165. Historically, this enzyme has been an extremely important model system for understanding the fundamentals of biological catalysis. TIM is activated through an energetically demanding conformational cha

Capturing the Role of Explicit Solvent in the Dimerization of RuV(bda) Water Oxidation Catalysts

A ground-breaking empirical valence bond study for a soluble transition-metal complex is presented. The full reaction of catalyst monomers approaching and reacting in the RuV oxidation state were studied. Analysis of the solvation shell in the reactant and along the reaction coordinate revealed that the oxo itself is hydrophobic, which adds a significant driving force to form the dimer. The effect

Active Site Hydrophobicity and the Convergent Evolution of Paraoxonase Activity in Structurally Divergent Enzymes : The Case of Serum Paraoxonase 1

Serum paraoxonase 1 (PON1) is a native lactonase capable of promiscuously hydrolyzing a broad range of substrates, including organophosphates, esters, and carbonates. Structurally, PON1 is a six-bladed β-propeller with a flexible loop (residues 70-81) covering the active site. This loop contains a functionally critical Tyr at position 71. We have performed detailed experimental and computational a

CADEE : Computer-Aided Directed Evolution of Enzymes

The tremendous interest in enzymes as biocatalysts has led to extensive work in enzyme engineering, as well as associated methodology development. Here, a new framework for computer-aided directed evolution of enzymes (CADEE) is presented which allows a drastic reduction in the time necessary to prepare and analyze in silico semi-automated directed evolution of enzymes. A pedagogical example of th

Probing the mechanisms for the selectivity and promiscuity of methyl parathion hydrolase

Diverse organophosphate hydrolases have convergently evolved the ability to hydrolyse man-made organophosphates. Thus, these enzymes are attractive model systems for studying the factors shaping enzyme functional evolution. Methyl parathion hydrolase (MPH) is an enzyme from the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphate, aryl ester and lactone substrates. In

Hypercompetition in biomedical research evaluation and its impact on young scientist careers

Recent years have seen tremendous changes in the modes of publication and dissemination of biomedical information, with the introduction of countless new publishers and publishing models, as well as alternative modes of research evaluation. In parallel, we are witnessing an unsustainable explosion in the amount of information generated by each individual scientist, at the same time as many countri

The Competing Mechanisms of Phosphate Monoester Dianion Hydrolysis

Despite the numerous experimental and theoretical studies on phosphate monoester hydrolysis, significant questions remain concerning the mechanistic details of these biologically critical reactions. In the present work we construct a linear free energy relationship for phosphate monoester hydrolysis to explore the effect of modulating leaving group pKa on the competition between solvent- and subst

Laboratory-Evolved Enzymes Provide Snapshots of the Development of Enantioconvergence in Enzyme-Catalyzed Epoxide Hydrolysis

Engineered enzyme variants of potato epoxide hydrolase (StEH1) display varying degrees of enrichment of (2R)-3-phenylpropane-1,2-diol from racemic benzyloxirane. Curiously, the observed increase in the enantiomeric excess of the (R)-diol is not only a consequence of changes in enantioselectivity for the preferred epoxide enantiomer, but also to changes in the regioselectivity of the epoxide ring o

Characterization of Mn(II) ion binding to the amyloid-β peptide in Alzheimer's disease

Growing evidence links neurodegenerative diseases to metal exposure. Aberrant metal ion concentrations have been noted in Alzheimer's disease (AD) brains, yet the role of metals in AD pathogenesis remains unresolved. A major factor in AD pathogenesis is considered to be aggregation of and amyloid formation by amyloid-β (Aβ) peptides. Previous studies have shown that Aβ displays specific binding to

Where are the female science professors? : A personal perspective

The first woman to earn a Professorship at a University in Europe was Laura Maria Caterina Bassi, who earned a professorship in physics at the University of Bologna in 1732. Almost 300 years and three waves of feminism later, in 2016, women typically still only comprise 20% (or less) of the number of full professors in Europe. This opinion article will discuss the experiences of being a female aca

Promiscuity in the Enzymatic Catalysis of Phosphate and Sulfate Transfer

The enzymes that facilitate phosphate and sulfate hydrolysis are among the most proficient natural catalysts known to date. Interestingly, a large number of these enzymes are promiscuous catalysts that exhibit both phosphatase and sulfatase activities in the same active site and, on top of that, have also been demonstrated to efficiently catalyze the hydrolysis of other additional substrates with

Conformational diversity and enantioconvergence in potato epoxide hydrolase 1

Potato epoxide hydrolase 1 (StEH1) is a biocatalytically important enzyme that exhibits rich enantio- and regioselectivity in the hydrolysis of chiral epoxide substrates. In particular, StEH1 has been demonstrated to enantioconvergently hydrolyze racemic mixes of styrene oxide (SO) to yield (R)-1-phenylethanediol. This work combines computational, crystallographic and biochemical analyses to under

Linking coupled motions and entropic effects to the catalytic activity of 2-deoxyribose-5-phosphate aldolase (DERA)

DERA, 2-deoxyribose-5-phosphate aldolase, catalyzes the retro-aldol cleavage of 2-deoxy-ribose-5-phosphate (dR5P) into glyceraldehyde-3-phosphate (G3P) and acetaldehyde in a branch of the pentose phosphate pathway. In addition to the physiological reaction, DERA also catalyzes the reverse addition reaction and, hence, is an interesting candidate for bio-catalysis of carbo-ligation reactions, which

Promiscuity and electrostatic flexibility in the alkaline phosphatase superfamily

Catalytic promiscuity, that is, the ability of single enzymes to facilitate the turnover of multiple, chemically distinct substrates, is a widespread phenomenon that plays an important role in the evolution of enzyme function. Additionally, such pre-existing multifunctionality can be harnessed in artificial enzyme design. The members of the alkaline phosphatase superfamily have served extensively

Expanding the Catalytic Triad in Epoxide Hydrolases and Related Enzymes

Potato epoxide hydrolase 1 exhibits rich enantio- and regioselectivity in the hydrolysis of a broad range of substrates. The enzyme can be engineered to increase the yield of optically pure products as a result of changes in both enantio- and regioselectivity. It is thus highly attractive in biocatalysis, particularly for the generation of enantiopure fine chemicals and pharmaceuticals. The presen

Exceptionally large entropy contributions enable the high rates of GTP hydrolysis on the ribosome

Protein synthesis on the ribosome involves hydrolysis of GTP in several key steps of the mRNA translation cycle. These steps are catalyzed by the translational GTPases of which elongation factor Tu (EF-Tu) is the fastest GTPase known. Here, we use extensive computer simulations to explore the origin of its remarkably high catalytic rate on the ribosome and show that it is made possible by a very l