O Teleman

VTT Technical Research Centre of Finland, Esbo, Southern Finland Province, Finland

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Publications (55)146.55 Total impact

  • L. KUUTTI, J. PELTONEN, J. PERE, O. TELEMAN
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    ABSTRACT: SummaryA combination of molecular modelling and atomic force microscopy (AFM) techniques was used to study the surface structure of crystalline cellulose. Two-dimensional Fourier analysis of the AFM raw data gave crystal parameters as well as a highly filtered inverse-transformed image. Molecular modelling was used to generate Connolly surfaces based on electron diffraction data for crystalline cellulose. The modelled surfaces were used to interpret the experimental AFM images. Monoclinic () crystal faces were identified. The method used enables the structural analysis of cellulose surfaces at the molecular level, where all biological processes involving cellulose take place.
    Journal of Microscopy 08/2011; 178(1):1 - 6. · 1.63 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 28(5).
  • Olle Teleman, Bo Jönsson
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    ABSTRACT: A molecular dynamics program for arbitrary molecular mixtures is presented. All intramolecular degrees of freedom are treated explicitly, which means that the program is based on central forces only. A double time step technique has been devised in order to separate rapidly varying, covalent forces from slowly varying ones. Typically, the ratio between the different time steps is about 10, with only a minor computational effort spent in the evaluation of the covalent forces. The program source code is arranged so as to obtain maximal efficiency on a vector processor, while still being portable. On a Cray 1A, a typical simulation of an ion-chelate in aqueous solution with 984 atoms requires a total of 29 μs/interaction with a spherical cutoff distance of 10Å.
    Journal of Computational Chemistry 08/2004; 7(1):58 - 66. · 3.84 Impact Factor
  • Olle. Teleman, Peter. Ahlstroem
    Journal of The American Chemical Society - J AM CHEM SOC. 04/2002; 108(15).
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    ABSTRACT: A molecular dynamics simulation of the Ca{sup 2+}-binding protein calbindin D{sub 9k} is reported. The calcium-saturated protein is simulated in an aqueous environment with an X-ray diffraction structure as the starting point. The simulation, which lasted 39 + 124 ps, was performed with the molecular dynamics program MUMOD. Structural and dynamic properties were investigated and compared with experiment. The protein contracts compared to the crystal form during the equilibration. The major contribution to the electrostatic part of the Ca{sup 2+}-binding energy arises from the amino acids of the Ca{sup 2+}-binding loops with only marginal contributions from the flanking helices. The estimated global rotational diffusion is faster than in experimental studies. From the simulation a characteristic time for a local reorientation process of the single tyrosine (Tyr 13) is estimated to 0.02-0.06 ns. More long-lived processes are present, but poor sampling precludes comparison with the experimental characteristic time of 0.36 ns obtained from fluorescence depolarization measurements. The simulated relaxation rates for {sup 43}Ca in the two binding sites are in qualitative agreement with and corroborate the assignments made in a recent experimental study.
    Biochemistry 04/2002; · 3.38 Impact Factor
  • Johan Koerdel, Olle Teleman
    Journal of the American Chemical Society 04/2002; 114(12). · 10.68 Impact Factor
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    ABSTRACT: The plasma phospholipid transfer protein (PLTP) is an important regulator of high density lipoprotein (HDL) metabolism. We have here, based on sequence alignments of the plasma LPS-binding/lipid transfer protein family and the X-ray structure of the bactericidal/permeability increasing protein (BPI), modeled the structure of PLTP. The model predicts a two-domain architecture with conserved lipid-binding pockets consisting of apolar residues in each domain. By site-directed mutagenesis of selected amino acid residues and transient expression of the protein variants in HeLa cells, the pockets are shown to be essential for PLTP-mediated phospholipid transfer. A solid phase ligand binding assay was used to determine the HDL-binding ability of the mutants. The results suggest that the observed decreases in phospholipid transfer activity of the N-terminal pocket mutants cannot be attributed to altered HDL-binding, but the C-terminal lipid-binding pocket may be involved in the association of PLTP with HDL. Further, the essential structural role of a disulfide bridge between cysteine residues 146 and 185 is demonstrated. The structural model and the mutants characterized here provide powerful tools for the detailed analysis of the mechanisms of PLTP function.
    The Journal of Lipid Research 07/1999; 40(6):1123-30. · 4.39 Impact Factor
  • Atherosclerosis 01/1999; 144:85-85. · 3.71 Impact Factor
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    ABSTRACT: The adsorption of various monomethylated π-extended viologen compounds onto self-assembled layers of octadecylmercaptan (ODM) on gold was investigated with secondary ion mass spectroscopy (SIMS) and atomic force microscopy (AFM). SIMS results indicated that the monomethylated viologen 5-(4-pyridyl)-5′-[4-(N-methyl)pyridinio]-2,2′-bithiophene iodide (PT2) adsorbed much more strongly onto the ODM self-assembled layers at 50 μM adsorption concentration in ethanol, while very similar compounds were much less effective in their adsorption even at much higher adsorption concentrations. The formation of multilayers of PT2 could be observed by AFM. Some structural features of the viologens, (dipole moment and polarizability), were calculated with semi-empirical quantum chemical calculations (MOPAC/AM1). One compound, PF2, having a slightly larger molecular length, dipole moment and polarizability than PT2, did not assemble noticeably onto the surface due to its larger solubility. The large difference in efficiency of adsorption can be related to a combination of length and absence of hydrophilic groups at the free pyridine side of the monomethylated viologens.
    Thin Solid Films 02/1998; 330:114. · 1.87 Impact Factor
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    ABSTRACT: Atomic force microscopy (AFM) and friction force microscopy (FFM) have been used to characterize the ageing of thermoplastic starch (TPS) films prepared by the extrusion technique, using water and glycerol as plasticizers. The fresh oat and barley starch films (1 week after extrusion) have flat and homogeneous surfaces. In the older starch films (2–5 weeks), the surface roughness has changed and the friction images reveal surface heterogeneity. The structural changes are supported by the tip-sample force–distance curve analysis. The changes in the structural properties during ageing i.e. starch–glycerol phase separation, crystallization of starch, or reorientation of polymers, are discussed.
    Carbohydrate Polymers. 01/1998;
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    ABSTRACT: Molecular Dynamic (MD) simulations were performed for the four surfaces of native crystalline cellulose. In all cases, only the topmost surface layer of the crystalline cellulose is structurally affected by the water outside the surface. Except for the glucose orientation repeat symmetry, the monoclinic 110 surface and the triclinic 010 surfaces are very similar. Likewise, the monoclinic 1-10 surface is very similar to the triclinic 100 surface. The two latter surfaces are denser and were found to be more hydrophilic than the two former. All surface layer molecules are equivalent in the monoclinic 110 and triclinic 010 surfaces, i.e., the odd/even duplicity breaks down for the monoclinic 110 surface. On the other hand, alternate molecules have different geometric and energetic properties in the monoclinic 1-10 and triclinic 100 surfaces, such that solvation of the triclinic 100 surface induces a translational asymmetry reminiscent of the monoclinic form. The results are discussed with respect to electron microscopy, scanning force microscopy, solid state NMR and protein binding data.
    Carbohydrate Research 01/1998; · 2.04 Impact Factor
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    ABSTRACT: Protein S (PS), which functions as a species-specific anticoagulant cofactor to activated protein C (APC), is a mosaic protein that interacts with the phospholipid membrane via its gamma-carboxyglutamate-rich (Gla) module. This module is followed by the thrombin-sensitive region (TSR), sensitive to thrombin cleavage, four epidermal growth factor (EGF)-like modules and a last region referred to as the sex hormone binding globulin (SHBG) domain. Of these, the TSR and the first EGF-like regions have been shown to be important for the species-specific interaction with APC. Difficulties in crystallising PS have so far hindered its study at the atomic level. Here, we report theoretical models for the Gla and EGF-1 modules of human PS constructed using prothrombin and factor X experimental structures. The TSR was built interactively. Analysis of the model linked with the large body of biochemical literature on PS and related proteins leads to suggestions that (i) the TSR stabilises the calcium-loaded Gla module through hydrophobic and ionic interactions and its conformation depends on the presence of the Gla module; (ii) the TSR does not form a calcium binding site but is protected from thrombin cleavage in the calcium-loaded form owing to short secondary structure elements and close contact with the Gla module; (iii) the PS missense mutations in this region are consistent with the structural data, except in one case which needs further investigation; and (iv) the two PS 'faces' involving regions of residues Arg49-Gln52-Lys97 (TSR-EGF-1) and Thr103-Pro106 (EGF-1) may be involved in species-specific interactions with APC as they are richer in nonconservative substitution when comparing human and bovine protein S. This preliminary model helps to plan future experiments and the resulting data will be used to further validate and optimise the present structure.
    Journal of Computer-Aided Molecular Design 06/1997; 11(3):293-304. · 3.17 Impact Factor
  • Andreas P. Heiner, Olle Teleman
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    ABSTRACT: The interface between the (110) crystal face of cellulose Iβ and water was studied by molecular dynamics simulation with cellulose coordinates refined from electron diffraction data as a starting point. Potential energies, pucker parameters, torsion angles, and hydrogen bonding have been used for the characterization. Only the topmost layer in the cellulose differs in terms of structure and dynamics from the crystal bulk, but even these difference are small. At the surface approximately half of the cellulose intermolecular hydrogen bonding is lost, but this is compensated by hydrogen bonds with water molecules. Much of the difference between even and odd (200) planes disappears at the interface, except for the orientation of the glucose ring plane. Water dynamics is retarded by a factor of 2−3 close to the surface. The potential energy of water molecules in the first hydration layer is lower by 2 kJ/mol. The cellulose surface contains about five exposed hydroxyl groups per square nanometer, which accounts for the good hydration of the surface.
    Langmuir. 02/1997; 13(3).
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    ABSTRACT: An anti-estradiol antibody with improved specificity is searched for by combining steroid analog binding studies, mutant antibodies obtained from a phage-display library and structural modeling. Three-dimensional models for the anti-estradiol antibody 57-2 were constructed by comparative model building. Estradiol and analogs were docked into the combining site and molecular dynamics simulation was used to further refine this area of the protein. Cross-reactivities measured against 36 steroid analogs were used to help in the docking process and to evaluate the models. The roles of a number of residues were assessed by characterization of cross-reactivity mutants obtained from a phage display library. The cross-reactivity data and the results observed for mutants are explained by the structural model, in which the estradiol D-ring inserts deeply into the binding site and interacts with the antibody through at least one specific hydrogen bond. The binding data strongly suggest that this hydrogen bond connects the estradiol 17-hydroxyl group with the side chain of Gln H35. As expected for the binding of a small aromatic molecule, the antibody binding site contains many aromatic residues, e.g. Trp H50, H95 and L96 and Tyr L32, L49 and Phe L91.
    Molecular Immunology 01/1997; 34(16-17):1215-26. · 2.65 Impact Factor
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    Annals of the New York Academy of Sciences 11/1996; 799:129-38. · 4.38 Impact Factor
  • The Journal of Organic Chemistry 10/1996; 61(19):6723-6726. · 4.56 Impact Factor
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    ABSTRACT: The hydrolysis of soluble cello-oligosaccharides, with a degree of polymerisation of 4-6, catalysed by cellobiohydrolase II from Trichoderma reesei was studied using 1H-NMR spectroscopy and HPLC. The experimental progress curves were analysed by fitting numerically integrated kinetic equations, which provided cleavage patterns and kinetic constants for each oligosaccharide. This analysis procedure accounts for product inhibition and avoids the initial slope approximation. No glucose was detected at the beginning of the reaction indicating that only the internal glycosidic linkages are attacked. For cellotetraose only the second glycosidic linkage was cleaved. For cellopentaose and cellohexaose the second and the third glycosidic linkage from the non-reducing end were cleaved with approximately equal probability. The degradation rates of these cello-oligosaccharides, 1-12 s-1 at 27 degrees C, are about 10-100 times faster than for the 4-methylumbelliferyl substituted analogs or for collotriose. No intermediate products larger than cellotriose were released. The degradation rate for cellotetraose were higher than its off-rate, which accounts for the processive degradation of cellohexaose. A high cellohexaose/enzyme ratio caused slow reversible inactivation of the enzyme.
    European Journal of Biochemistry 10/1996; 240(3):584-91. · 3.58 Impact Factor
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    ABSTRACT: Trichoderma reesei cellobiohydrolase II (CBHII) is an exoglucanase cleaving primarily cellobiose units from the non-reducing end of cellulose chains. The beta-1,4 glycosidic bond is cleaved by acid catalysis with an aspartic acid, D221, as the likely proton donor, and another aspartate, D175, probably ensuring its protonation and stabilizing charged reaction intermediates. The catalytic base has not yet been identified experimentally. The refined crystal structure of CBHII also shows a tyrosine residue, Y169, located close enough to the scissile bond to be involved in catalysis. The role of this residue has been studied by introducing a mutation Y169F, and analysing the kinetic and binding behavior of the mutated CBHII. The crystal structure of the mutated enzyme was determined to 2.0 A resolution showing no changes when compared with the structure of native CBHII. However, the association constants of the mutant enzyme for cellobiose and cellotriose are increased threefold and for 4-methylumbelliferyl cellobioside over 50-fold. The catalytic constants towards cellotriose and cellotetraose are four times lower for the mutant. These data suggest that Y169, on interacting with a glucose ring entering the second subsite in a narrow tunnel, helps to distort the glucose ring into a more reactive conformation. In addition, a change in the pH activity profile was observed. This indicates that Y169 may have a second role in the catalysis, namely to affect the protonation state of the active site carboxylates, D175 and D221.
    Protein engineering 09/1996; 9(8):691-9.
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    ABSTRACT: Prostate-specific antigen (PSA), produced by prostate cells, provides an excellent serum marker for prostate cancer. It belongs to the human kallikrein family of enzymes, a second prostate-derived member of which is human glandular kallikrein-1 (hK2). Active PSA and hK2 are both 237-residue kallikrein-like proteases, based on sequence homology. An hK2 model structure based on the serine protease fold is presented and compared to PSA and six other serine proteases in order to analyze in depth the role of the surface-accessible loops surrounding the active site. The results show that PSA and hK2 share extensive structural similarity and that most amino acid replacements are centered on the loops surrounding the active site. Furthermore, the electrostatic potential surfaces are very similar for PSA and hK2. PSA interacts with at least two serine protease inhibitors (serpins): alpha-1-antichymotrypsin (ACT) and protein C inhibitor (PCI). Three-dimensional model structures of the uncleaved ACT molecule were developed based upon the recent X-ray structure of uncleaved antithrombin. The serpin was docked both to PSA and hK2. Amino acid replacements and electrostatic complementarities indicate that the overall orientation of the proteins in these complexes is reasonable. In order to investigate PSA's heparin interaction sites, electrostatic computations were carried out on PSA, hK2, protein C, ACT, and PCI. Two heparin binding sites are suggested on the PSA surface and could explain the enhanced complex formation between PSA and PCI, while inhibiting the formation of the ACT-PSA complex, PSA, hK2, and their preliminary complexes with ACT should facilitate the understanding and prediction of structural and functional properties for these important proteins also with respect to prostate diseases.
    Protein Science 06/1996; 5(5):836-51. · 2.74 Impact Factor