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  • 101.
    Samuelsson, Johan Patrik
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Jonsson, Mats
    KTH, Tidigare Institutioner, Kemi.
    Brinck, Tore
    KTH, Tidigare Institutioner, Kemi.
    Johansson, Mats K. G.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Thiol-ene coupling reaction of fatty acid monomers2004Inngår i: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 42, nr 24, s. 6346-6352Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reactivities and reaction rates of the thiol-ene coupling reaction of 2-ethyl-(hydroxymethyl)-1,3-propanediol trimercapto acetate and 2-ethyl-(hydroxymethyl)-1,3-propanediol trimercapto propionate with two common unsaturated fatty acid methyl esters (methyl oleate and methyl linoleate) were evaluated. The reactions were monitored with real-time IR and H-1 NMR, which both showed that the mercapto acetate was more reactive than the mercapto propionate. Both thiols were more prone to add to the monounsaturated methyl oleate than to methyl linoleate, which contained two unconjugated double bonds. According to bond energy calculations, the thiol hydrogen of mercapto acetate was somewhat more difficult to abstract than the hydrogen of mercapto propionate. Consequently, the formed S-C bond in the acetate case was stronger than in the propionate case, and so the equilibrium was more shifted toward the addition products. The real-time IR measurements also showed that the cis unsaturation in methyl oleate isomerized much more quickly than that in methyl linoleate, and this also had an impact on the overall addition rate of the thiols because a trans unsaturation was more reactive than a cis unsaturation. The higher isomerization rates in the oleate systems, compared with those of the linoleate systems, was suggested to be due to a more restricted rotation along the C-C bond of the reacted unsaturation in linoleate. This study showed the importance of trans unsaturations in obtaining reasonable reaction rates in thiol-ene reactions with fatty acid derivatives.

  • 102.
    Soldemo, Markus
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Halldin Stenlid, Joakim
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Besharat, Zahra
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Ghadami Yazdi, Milad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Önsten, Anneli
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Weissenrieder, Jonas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    The Surface Structure of Cu2O(100)2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 8, s. 4373-4381Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite the industrial importance of copper oxides, the nature of the (100) surface of Cu2O has remained poorly understood. The surface has previously been subject to several theoretical and experimental studies, but has until now not been investigated by atomically resolved microscopy or high-resolution photoelectron spectroscopy. Here we determine the atomic structure and electronic properties of Cu2O(100) by a combination of multiple experimental techniques and simulations within the framework of density functional theory (DFT). Low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) characterized the three ordered surface structures found. From DFT calculations, the structures are found to be energetically ordered as (3,0;1,1), c(2 x 2), and (1 x 1) under ultrahigh vacuum conditions. Increased oxygen pressures induce the formation of an oxygen terminated (1 x 1) surface structure. The most common termination of Cu2O(100) has previously been described by a (3 root 2 x root 2)R45 degrees unit cell exhibiting a LEED pattern with several missing spots. Through atomically resolved STM, we show that this structure instead is described by the matrix (3,0;1,1). Both simulated STM images and calculated photoemission core level shifts compare favorably with the experimental results.

  • 103.
    Soldemo, Markus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Materialfysik, MF.
    Halldin Stenlid, Joakim
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Besharat, Zahra
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Materialfysik, MF.
    Johansson, N.
    Önsten, Anneli
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Materialfysik, MF.
    Knudsen, J.
    Schnadt, J.
    Göthelid, Mats
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Materialfysik, MF.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Weissenrieder, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Materialfysik, MF.
    Interaction of Sulfur Dioxide and Near-Ambient Pressures of Water Vapor with Cuprous Oxide Surfaces2017Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, nr 43, s. 24011-24024Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction of water vapor and sulfur dioxide (SO2) with single crystal cuprous oxide (Cu2O) surfaces of (100) and (111) termination was studied by photoelectron spectroscopy (PES) and density functional theory (DFT). Exposure to near-ambient pressures of water vapor, at 5 × 10-3 %RH and 293 K, hydroxylates both Cu2O surfaces with OH coverage up to 0.38 copper monolayers (ML) for (100) and 0.25 ML for (111). O 1s surface core level shifts indicate that the hydroxylation lifts the (3,0;1,1) reconstruction of the clean (100) surface. On both clean Cu2O terminations, SO2 adsorbs to unsaturated surface oxygen atoms to form SO3 species with coverage, after a saturating SO2 dose, corresponding to 0.20 ML on the Cu2O(100) surface and 0.09 ML for the Cu2O(111) surface. Our combined DFT and PES results suggest that the SO2 to SO3 transformation is largely facilitated by unsaturated copper atoms at the Cu2O(111) surface. SO3-terminated surfaces exposed to low doses of water vapor (≤100 langmuirs) in ultrahigh vacuum show no adsorption or reaction. However, during exposure to near-ambient pressures of water vapor, the SO3 species dissociate, and sulfur replaces a Cu2O lattice oxygen in a reaction that forms Cu2S. The hydroxylation of the Cu2O surfaces is believed to play a central role in the reaction.

  • 104. Stenlid, Joakim H.
    et al.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Nucleophilic Aromatic Substitution Reactions Described by the Local Electron Attachment Energy2017Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, nr 6, s. 3072-3083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A local multiorbital electrophilicity descriptor, the local electron attachment energy [E(r)], is used to study the nucleophilic aromatic substitution reactions of SNAr and VNS (vicarious nucleophilic substitution). E(r) considers all virtual orbitals below the free electron limit and is determined on the molecular isodensity contour of 0.004 atomic units. Good (R-2 = 0.83) to excellent (R-2 = 0.98) correlations are found between descriptor values and experimental reactivity data for six series of electron deficient arenes. These include homo- and heteroarenes, rings of five to six atoms, and a variety of fluorine, bromine, and hydride leaving groups. The solvent, temperature, and nucleophile are in addition varied across the series. The surface E(r) [E-s(r)] is shown to provide reactivity predictions better than those of transition-state calculations for a concerted SNAr reaction with a bromine substantially stronger than those of LUMO energies, and is overall more reliable than the molecular electrostatic potential. With the use of E-s(r), one can identify the various electrophilic sites within a molecule and correctly predict isomeric distributions. Since the calculations of E-s(r) are computationally inexpensive, the descriptor offers fast but accurate reactivity predictions for the important nucleophilic aromatic substitution class of reactions. Applications in, e.g., drug discovery, synthesis, and toxicology studies are envisaged.

  • 105.
    Stenlid, Joakim H.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Johansson, A. Johannes
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Local Lewis Acidity of (TiO2)(n) (n=7-10) Nanoparticles Characterized by DFT-Based Descriptors: Tools for Catalyst Design2017Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, nr 49, s. 27483-27492Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transition metal oxide nanoparticles are common materials in a multitude of applications including heterogeneous catalysis, solar energy harvesting, and energy storage. Understanding the particles' interplay with their surroundings is key to their efficient usage and design. Herein two DFT-based descriptors are used to study local reactivity on (TiO2)(n) (n = 7-10) nanoparticles. The local electron attraction energy [E(r)] and the electrostatic potential [V(r)], evaluated on isodensity surfaces, are able to identify and rank Lewis acidic sites on the particles with high accuracy when compared to the interaction energies of the Lewis bases H2O, H2S, NH3, and CO. These interactions are characterized as mainly electrostatically controlled. Given the local character, low computational cost, and excellent performance of the E-s(r) and V-s(r) descriptors, they are anticipated to find widespread use in nanoparticle research and development.

  • 106.
    Svedendahl, Maria
    et al.
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Branneby, Cecilia
    Cambrex Karlskoga AB.
    Carlqvist, Peter
    KTH, Tidigare Institutioner, Kemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Hult, Karl
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Berglund, Per
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Michael-type additions catalyzed by a rationally redesigned lipase2004Konferansepaper (Fagfellevurdert)
  • 107.
    Svedendahl, Maria
    et al.
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Branneby, Cecilia
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Carlqvist, Peter
    KTH, Tidigare Institutioner, Kemi.
    Hult, Karl
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Brinck, Tore
    KTH, Tidigare Institutioner, Kemi.
    Berglund, Per
    KTH, Tidigare Institutioner, Biokemi och biokemisk teknologi.
    Expanding the Synthetic Scope of Hydrolytic Enzymes: Catalysis of Aldol- and Michael-Type Additions2004Konferansepaper (Fagfellevurdert)
  • 108.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Carlqvist, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Branneby, Cecilia
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Allnér, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Frise, Anton
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    Direct Epoxidation in Candida antarctica Lipase B Studied by Experiment and Theory2008Inngår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, nr 15, s. 2443-2451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Candida antarctica lipase B (CALB) is a promiscuous serine hydrolase that, besides its native function, catalyzes different side reactions, such as direct epoxidation. A single-point mutant of CALB demonstrated a direct epoxidation reaction mechanism for the epoxidation of alpha,beta-unsaturated aldehydes by hydrogen peroxide in aqueous and organic solution. Mutation of the catalytically active Ser105 to alanine made the previously assumed indirect epoxidation reaction mechanism impossible. Gibbs free energies, activation parameters, and substrate selectivities were determined both computationally and experimentally. The energetics and mechanism for the direct epoxidation in CALB Ser105Ala were investigated that the reaction proceeds through a two step-mechanism with formation of an oxyanionic intermediate. The active-site residue His224 functions as a general acid-base catalyst with support from Asp187. Oxyanion stabilization is facilitated by two hydrogen bonds from Thr40.

  • 109.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Catalytic Promiscuity of a Lipase for Direct Epoxidation Reactions2007Inngår i: / [ed] Vicente Gotor, 2007Konferansepaper (Fagfellevurdert)
  • 110.
    Svedendahl, Maria
    et al.
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Hult, Karl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Promiscuous Reactions in Candida antarctica lipase B2008Konferansepaper (Fagfellevurdert)
  • 111.
    Tissot, Heloise
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Wang, Chunlei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Sterdid, Joakim Halldin
    Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Weissenrieder, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    The Surface Structure of Cu2O(100): Nature of Defects2019Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 13, s. 7696-7704Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cu2O(100) surface is most favorably terminated by a (3,0;1,1) reconstruction under ultrahigh-vacuum conditions. As most oxide surfaces, it exhibit defects, and it is these sites that are focus of attention in this study. The surface defects are identified, their properties are investigated, and procedures to accurately control their coverage are demonstrated by a combination of scanning tunneling microscopy (STM) and simulations within the framework of density functional theory (DFT). The most prevalent surface defect was identified as an oxygen vacancy. By comparison of experimental results, formation energies, and simulated STM images, the location of the oxygen vacancies was identified as an oxygen vacancy in position B, located in the valley between the two rows of oxygen atoms terminating the unperturbed surface. The coverage of defects is influenced by the surface preparation parameters and the history of the sample. Furthermore, using low-energy electron beam bombardment, we show that the oxygen vacancy coverage can be accurately controlled and reach a complete surface coverage (1 per unit cell or 1.8 defects per nm(2)) without modification to the periodicity of the surface, highlighting the importance of using local probes when investigating oxide surfaces.

  • 112.
    Vongvilai, Pornrapee
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Linder, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Sakulsombat, Morakot
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Humble, Maria Svedendahl
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Racemase Activity of B. cepacia Lipase Leads to Dual-Function Asymmetric Dynamic Kinetic Resolution of alpha-Aminonitriles2011Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, nr 29, s. 6592-6595Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Applaudable promiscuity: Racemase-type activity discovered for B. cepacia lipase with N-substituted α-aminonitriles is proposed to involve a C-C bond-breaking/forming mechanism in the hydrolase site of the enzyme, as supported by experimental data and calculations. This promiscuous activity in combination with the transacylation activity of the enzyme enabled the asymmetric synthesis of N-methyl α-aminonitrile amides in high yield (see scheme).

  • 113. Wallin, S.
    et al.
    Östmark, H.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Norrefeldt, M.
    Rehn, S.
    Novel high energetic materials: Calculations and synthesis attempts of metal pentazolates by electrochemistry2006Inngår i: Proceedings of the 13th International Detonation Symposium, 2006, s. 263-272Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Electrochemical synthesis has been used to selectively cleave of the nitrogen ring from p-methoxyphenylpentazole. Evidence suggesting that the pentazole ring leaves the molecule as one entity is presented. The results of quantum chemical calculations supporting and enabling the experimental work are also presented.

  • 114.
    Woldegiorgis, Andreas
    et al.
    KTH, Tidigare Institutioner, Kemi.
    von Kieseritzky, Fredrik
    KTH, Tidigare Institutioner, Kemi.
    Dahlstedt, Emma
    KTH, Tidigare Institutioner, Kemi.
    Hellberg, Jonas
    KTH, Tidigare Institutioner, Kemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630).
    Roeraade, Johan
    KTH, Tidigare Institutioner, Kemi.
    Polymer-assisted laser desorption/ionization analysis of small molecular weight compounds2004Inngår i: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 18, nr 8, s. 841-852Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of non-polar, small polymers as matrices for the analysis of low molecular weight compounds in polymer-assisted laser desorption/ionization mass spectrometry (PALDI-MS) is demonstrated. The matrices evaluated were either based on an oligothiophene or a benzodioxin backbone. Metallocenes, polycyclic hydrocarbons, a fluorosurfactant, and a subset of small organic compounds with various functionalities, served as model analytes. The mechanism of ionization charge transfer is discussed and ionization potentials for the matrices in the study have been estimated using density functional theory (DFT) calculations. Some of the results are possibly contradictory to the generally accepted limiting conditions for gas-phase charge-transfer reactions. These results are interpreted in the light of energy pooling. Also a new mass calibration procedure for the lowmass region in positive ion mode is presented, and some aspects of the ionization/desorption process leading to radical cations are studied.

  • 115.
    Zhang, Fan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Brandner, Birgit
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Dédinaité, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    In situ confocal Raman micro-spectroscopy and electrochemical studies of mussel adhesive protein and ceria composite film on carbon steel in salt solutions2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 107, s. 276-291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films composed of Mefp-1 and ceria nanoparticles have shown an increasing corrosion inhibition effect with time for carbon steel in acidic aqueous solutions containing phosphate, which motivates a detailed study of the inhibition mechanism by in situ confocal Raman micro-spectroscopy (CRM) and electrochemical impedance spectroscopy (EIS) measurements. The presence of both CeO2 and ferric oxides in the thin composite film was demonstrated by X-ray photoelectron spectroscopy analysis. The Raman spectra assisted by DFT calculations suggest that Mefp-1 forms tri-Fe3+/Mefp-1 complexes and binds to ceria nanoparticles in the composite film. The in situ CRM measurement allow us to follow the development of corrosion products. The measurements show a mixture of Fe oxides/oxyhydroxides, and also indicate that ferrous oxides may be further oxidized by the composite film. Moreover, phosphate ions react with the Fe ions released from the surface to form iron-phosphate deposits, which become incorporated into the corrosion product layer and the composite film. The EIS measurements suggest a layered surface structure formed by the initial Mefp-1/ceria composite layer and the corrosion products/iron-phosphate deposits. These measurements also demonstrate the greatly increased inhibition effect of the composite film in the presence of the phosphate ions. The consistent CRM and EIS results suggest that the iron-phosphate deposits heal defects in the composite film and corrosion product layer, which results in a significantly improved corrosion inhibition of the Mefp-1/ceria composite film during initial and long term exposure.

  • 116.
    Zhang, Fan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Claesson, Per Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Electrochemical, atomic force microscopy and infrared reflection absorption spectroscopy studies of pre-formed mussel adhesive protein films on carbon steel for corrosion protection2012Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 24, s. 7136-7143Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochemical measurements, in situ and ex situ atomic force microscopy (AFM) experiments and infrared reflection absorption spectroscopy (IRAS) analysis were performed to investigate the formation and stability as well as corrosion protection properties of mussel adhesive protein (Mefp-1) films on carbon steel, and the influence of cross-linking by NaIO 4 oxidation. The in situ AFM measurements show flake-like adsorbed protein aggregates in the film formed at pH 9. The ex situ AFM images indicate multilayer-like films and that the film becomes more compact and stable in NaCl solution after the cross-linking. The IRAS results reveal the absorption bands of Mefp-1 on carbon steel before and after NaIO 4 induced oxidation of the pre-adsorbed protein. Within a short exposure time, a certain corrosion protection effect was noted for the pre-formed Mefp-1 film in 0.1 M NaCl solution. Cross-linking the pre-adsorbed film by NaIO 4 oxidation significantly enhanced the protection efficiency by up to 80%.

  • 117.
    Zhang, Fan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Sababi, Majid
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Persson, Dan
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces.
    In situ investigations of Fe3+ induced complexation of adsorbed Mefp-1 protein film on iron substrate2013Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 404, s. 62-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A range of in situ analytical techniques and theoretical calculations were applied to gain insights into the formation and properties of the Mefp-I film on iron substrate, as well as the protein complexation with Fe3+ ions. Adsorption kinetics of Mefp-1 and the complexation were investigated using QCM-D. The results suggest an initially fast adsorption, with the molecules oriented preferentially parallel to the surface, followed by a structural change within the film leading to molecules extending toward solution. Exposure to a diluted FeCl3 solution results in enhanced complexation within the adsorbed protein film, leading to water removal and film compaction. In situ Peak Force Tapping AFM was employed for determining morphology and nano-mechanical properties of the surface layer. The results, in agreement with the QCM-D observations, demonstrate that addition of Fe-3 induces a transition from an extended and soft protein layer to a denser and stiffer one. Further, in situ ATR-FTIR and Confocal Raman Micro-spectroscopy (CRM) techniques were utilized to monitor compositional/structural changes in the surface layer due to addition of Fe3+ ions. The spectroscopic analyses assisted by DFT calculations provide evidence for formation of tri-Fe3+/catechol complexes in the surface film, which is enhanced by Fe3+ addition.

  • 118.
    Öberg, Helena
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Fragment molecular orbital study of the cAMP-dependent protein kinase catalyzed phosphoryl transfer: a comparison with the differential transition state stabilization method2016Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 22, s. 15153-15161Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The importance of key residues to the activity of the cAMP-dependent protein kinase catalyzed phosphoryl transfer and to the stabilization of the transition state of the reaction has been investigated by means of the fragment molecular orbital (FMO) method. To evaluate the accuracy of the method and its capability of fragmenting covalent bonds, we have compared stabilization energies due to the interactions between individual residues and the reaction center to results obtained with the differential transition state stabilization method (Szarek, et al., J. Phys. Chem. B, 2008, 112, 11819-11826) and observe, despite a size difference in the fragment describing the reaction center, near-quantitative agreement. We have also computed deletion energies to investigate the effect of virtual deletion of key residues on the activation energy. These results are consistent with the stabilization energies and yield additional information as they clearly capture the effect of secondary interactions, i. e. interactions in the second coordination layer of the reaction center. We find that using FMO to calculate deletion energies is a powerful and time efficient approach to analyze the importance of key residues to the activity of an enzyme catalyzed reaction.

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