| 1. |
- Katz, A., et al.
(författare)
-
Experimental and theoretical study of the movement of the wpd flexible loop of human protein tyrosine phosphatase PTP1B in complex with halide ions
- 2012
-
Ingår i: Biophysical Reviews and Letters. - : World Scientific. ; 7:3-4, s. 197-217
-
Tidskriftsartikel (refereegranskat)abstract
- Protein tyrosine phosphorylation is a post-translational modification mechanism, crucial for the regulation of nearly all aspects of cell life. This dynamic, reversible process is regulated by the balanced opposing activity of protein tyrosine kinases and protein tyrosine phosphatases. In particular, the protein tyrosine phosphatase 1B (PTP1B) is implicated in the regulation of the insulin-receptor activity, leptin-stimulated signal transduction pathways and other clinically relevant metabolic routes, and it has been found overexpressed or overregulated in human breasts, colon and ovary cancers. The WPD loop of the enzyme presents an inherent flexibility, and it plays a fundamental role in the enzymatic catalysis, turning it into a potential target in the design of new efficient PTP1B inhibitors. In order to determine the interactions that control the spatial conformation adopted by the WPD loop, complexes between the enzyme and halide ions (Br- and I- in particular) were crystallized and their crystallographic structure determined, and the collective movements of the aforementioned complexes were studied through Molecular Dynamics (MD) simulations. Both studies yielded concordant results, indicating the existence of a relationship between the identity of the ion present in the complex and the strength of the interactions it establishes with the surrounding protein residues. © 2012 World Scientific Publishing Company.
|
|
| 2. |
- dos Santos, Daniel J V A, et al.
(författare)
-
Properties and behaviour of tetracyclic allopsoralen derivatives inside a DPPC lipid bilayer model.
- 2011
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 13:21, s. 10174-82
-
Tidskriftsartikel (refereegranskat)abstract
- Allopsoralens are angular psoralen derivatives presenting advantages over the parent compound because of monofunctional DNA-photobinding and consequent lower toxicity. Allopsoralen molecules with three different substituents and different protonation states were studied using the molecular dynamics technique. The location of these molecules when inside the lipid bilayer is of major importance because their photochemical properties can change with the environment. Also, the ability of psoralens to form photoadducts with unsaturated phospholipids depends on the preference of the molecules to locate themselves closer to the bilayer middle were the double bond functionality can be found. Herein we show that the allopsoralens tend to accumulate inside the lipid bilayer closer to the water interface when protonated or closer to the interface middle otherwise. Allopsoralens containing one amine terminated carbon chain tend to have different rotational and orientational behaviour and an orientation preference close to the ones shown by the lipids. The size and chemical nature of the substituent also affect the molecular mobility and capacity to interact with water molecules and the nitrogen or phosphorus atoms of the lipids.
|
|
| 3. |
- Saenz Mendez, Patricia, et al.
(författare)
-
Homology models of human all-trans retinoic acid metabolizing enzymes CYP26B1 and CYP26B1 spliced-variant.
- 2012
-
Ingår i: Journal of Chemical Information and Modeling. - Washington, USA : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 52:10, s. 2631-2637
-
Tidskriftsartikel (refereegranskat)abstract
- Homology models of CYP26B1 (cytochrome P450RAI2) and CYP26B1 spliced variant were derived using the crystal structure of cyanobacterial CYP120A1 as template for the model building. The quality of the homology models generated were carefully evaluated, and the natural substrate all-trans-retinoic acid (atRA), several tetralone-derived retinoic acid metabolizing blocking agents (RAMBAs), and a well-known potent inhibitor of CYP26B1 (R115866) were docked into the homology model of full-length cytochrome P450 26B1. The results show that in the model of the full-length CYP26B1, the protein is capable of distinguishing between the natural substrate (atRA), R115866, and the tetralone derivatives. The spliced variant of CYP26B1 model displays a reduced affinity for atRA compared to the full-length enzyme, in accordance with recently described experimental information.
|
|
| 4. |
- Askarieh, Glareh, et al.
(författare)
-
Self-assembly of spider silk proteins is controlled by a pH-sensitive relay
- 2010
-
Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 465:7295, s. 236-8
-
Tidskriftsartikel (refereegranskat)abstract
- Nature's high-performance polymer, spider silk, consists of specific proteins, spidroins, with repetitive segments flanked by conserved non-repetitive domains. Spidroins are stored as a highly concentrated fluid dope. On silk formation, intermolecular interactions between repeat regions are established that provide strength and elasticity. How spiders manage to avoid premature spidroin aggregation before self-assembly is not yet established. A pH drop to 6.3 along the spider's spinning apparatus, altered salt composition and shear forces are believed to trigger the conversion to solid silk, but no molecular details are known. Miniature spidroins consisting of a few repetitive spidroin segments capped by the carboxy-terminal domain form metre-long silk-like fibres irrespective of pH. We discovered that incorporation of the amino-terminal domain of major ampullate spidroin 1 from the dragline of the nursery web spider Euprosthenops australis (NT) into mini-spidroins enables immediate, charge-dependent self-assembly at pH values around 6.3, but delays aggregation above pH 7. The X-ray structure of NT, determined to 1.7 A resolution, shows a homodimer of dipolar, antiparallel five-helix bundle subunits that lack homologues. The overall dimeric structure and observed charge distribution of NT is expected to be conserved through spider evolution and in all types of spidroins. Our results indicate a relay-like mechanism through which the N-terminal domain regulates spidroin assembly by inhibiting precocious aggregation during storage, and accelerating and directing self-assembly as the pH is lowered along the spider's silk extrusion duct.
|
|
| 5. |
- Bermúdez, Eduardo, et al.
(författare)
-
Improved homology model of cyclohexanone monooxygenase from Acinetobacter calcoaceticus based on multiple templates
- 2014
-
Ingår i: Computational biology and chemistry. - : Elsevier BV. - 1476-9271 .- 1476-928X. ; 49, s. 14-22
-
Tidskriftsartikel (refereegranskat)abstract
- A new homology model of cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus is derived based on multiple templates, and in particular the crystal structure of CHMO from Rhodococcus sp. The derived model was fully evaluated, showing that the quality of the new structure was improved over previous models. Critically, the nicotinamide cofactor is included in the model for the first time. Analysis of several molecular dynamics snapshots of intermediates in the enzymatic mechanism led to a description of key residues for cofactor binding and intermediate stabilization during the reaction, in particular Arg327 and the well known conserved motif (FxGxxxHxxxW) in Baeyer-Villiger monooxygenases, in excellent agreement with known experimental and computational data. © 2014 Elsevier Ltd.
|
|
| 6. |
- Brovetto, Margarita, et al.
(författare)
-
C-C Bond-Forming Lyases in Organic Synthesis
- 2011
-
Ingår i: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 111:7, s. 4346-4403
-
Forskningsöversikt (refereegranskat)
|
|
| 7. |
- Elmabsout, Ali Ateia, et al.
(författare)
-
Cloning and Functional Studies of a Splice Variant of CYP26B1 Expressed in Vascular Cells
- 2012
-
Ingår i: Plos One. - San Francisco, USA : Public Library of Science (PLoS). - 1932-6203. ; 7:5
-
Tidskriftsartikel (refereegranskat)abstract
- Background: All-trans retinoic acid (atRA) plays an essential role in the regulation of gene expression, cell growth and differentiation and is also important for normal cardiovascular development but may in turn be involved in cardiovascular diseases, i.e. atherosclerosis and restenosis. The cellular atRA levels are under strict control involving several cytochromes P450 isoforms (CYPs). CYP26 may be the most important regulator of atRA catabolism in vascular cells. The present study describes the molecular cloning, characterization and function of atRA-induced expression of a spliced variant of the CYP26B1 gene. Methodology/Principal Findings: The coding region of the spliced CYP26B1 lacking exon 2 was amplified from cDNA synthesized from atRA-treated human aortic smooth muscle cells and sequenced. Both the spliced variant and full length CYP26B1 was found to be expressed in cultured human endothelial and smooth muscle cells, and in normal and atherosclerotic vessel. atRA induced both variants of CYP26B1 in cultured vascular cells. Furthermore, the levels of spliced mRNA transcript were 4.5 times higher in the atherosclerotic lesion compared to normal arteries and the expression in the lesions was increased 20-fold upon atRA treatment. The spliced CYP26B1 still has the capability to degrade atRA, but at an initial rate one-third that of the corresponding full length enzyme. Transfection of COS-1 and THP-1 cells with the CYP26B1 spliced variant indicated either an increase or a decrease in the catabolism of atRA, probably depending on the expression of other atRA catabolizing enzymes in the cells. Conclusions/Significance: Vascular cells express the spliced variant of CYP26B1 lacking exon 2 and it is also increased in atherosclerotic lesions. The spliced variant displays a slower and reduced degradation of atRA as compared to the full-length enzyme. Further studies are needed, however, to clarify the substrate specificity and role of the CYP26B1 splice variant in health and disease.
|
|
| 8. |
- Fagan, V., et al.
(författare)
-
COMPARE analysis of the toxicity of an iminoquinone derivative of the imidazo[5,4-f]benzimidazoles with NAD(P)H:quinone Oxidoreductase 1 (NQO1) activity and computational docking of quinones as NQO1 substrates
- 2012
-
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 20:10, s. 3223-3232
-
Tidskriftsartikel (refereegranskat)abstract
- Synthesis and cytotoxicity of imidazo[5,4-f]benzimidazolequinones and iminoquinone derivatives is described, enabling structure-activity relationships to be obtained. The most promising compound (an iminoquinone derivative) has undergone National Cancer Institute (NCI) 60 cell line (single and five dose) screening, and using the NCI COMPARE program, has shown correlation to NQO1 activity and to other NQO1 substrates. Common structural features suggest that the iminoquinone moiety is significant with regard to NQO1 specificity. Computational docking into the active site of NQO1 was performed, and the first comprehensive mitomycin C (MMC)-NQO1 docking study is presented. Small distances for hydride reduction and high binding affinities are characteristic of MMC and of iminoquinones showing correlations with NQO1 via COMPARE analysis. Docking also indicated that the presence of a substituent capable of hydrogen bonding to the His194 residue is important in influencing the orientation of the substrate in the NQO1 active site, leading to more efficient reduction. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 9. |
|
|
