Magnús Már Kristjánsson
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EMail: Address: Phone (office): Fax: |
Science Institute, University of Iceland +354 525 4819 +354 525 4725 +354 552 8911 |
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Research interests
The main focus of research in our group is on the structure function relationships of proteins as they relate to temperature adaptation. We are especially interested in determining which structural factors are responsible for the striking differences in both stability and catalytic properties often observed among homologous enzymes which have adapted to function at the extremes of temperature in the biosphere. A model protein for our research is a subtilisin-like serine proteinase (VPR) from a psychrophilic Vibrio-species, and the homologous enzymes, proteinase K (PRK) from the fungus Tritirachium album and aqualysin I (AQUI) from the thermophile Thermus aquaticus YT-1. These enzymes differ significantly with respect to catalytic activity and stability, reflecting their respective temperatures of adaptation. The known crystal structures of the psychrophilic VPR, the mesophilic PRK, and that of AQUI are the subjects of our structural comparison on which we base our hypotheses of the structural basis of their temperature adaptation, which we then test by site-directed mutagenesis. Several mutants of both VPR and AQUI have now been produced and characterized with respect to enzymatic, stability and dynamic properties.
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- Arnórsdóttir, J., Magnúsdóttir, M., Friðjónsson. Ó. H. and Kristjánsson, M. M. (2011) The effect of deleting a putative salt bridge on the properties of the thermostable subtilisin-like proteinase, aqualysin I. Protein Peptide lett. 18. 545-551.
- Sigurdardóttir, A. G., Arnórsdóttir, J., Thorbjarnardóttir, S. H., Eggertsson, G., Suhre, K. and Kristjánsson, M. M. (2009) Characteristics of mutants designed to incorporate a new ion pair into the structure of a cold adapted subtilisin-like serine proteinase, Biochim. Biophys. Acta 1794, 512-518 ; (doi:10.1016/j.bbapap.2008.11.018)
- Arnórsdóttir, J, Sigtryggsdóttir, Á. R., Thorbjarnardóttir, S. H. and Kristjánsson, M. M. (2009) Effect of proline substitutions on stability and kinetic properties of a cold adapted subtilase J. Biochem. 145, 325-329 ; (doi: 10.1093/jb/mvn168)
- Arnórsdóttir, J., Helgadóttir, S., Þorbjarnardóttir, S. H., Eggertsson, G. and Kristjánsson, M. M. (2007) Effect of selected Ser/Ala and Xaa/Pro mutations on the stability and catalytic properties of a cold adapted subtilisin-like serine proteinase. Biochim. Biophys. Acta 1774, 749-755.
- Arnórsdóttir, J., Kristjánsson, M. M. and Ficner, R. (2005) Crystal structure of a subtilisin-like serine protienase from a psychrotrophic Vibrio species reveals structural aspects of cold adaptation. FEBS Journal 272, 832-845.
- Arnórsdóttir, J., Smáradóttir, R. B., Magnússon, Ó. Th., Thorbjarnardóttir, S. H., Eggertsson, G. and Kristjánsson, M. M. (2002) Characterization of a cloned subtilisin-like serine proteinase from a psychrotrophic Vibrio-species. Eur. J. Biochem. 269, 5536-5546.
- Kristjánsson, M. M. and Ásgeirsson, B. (2002) Properties of extremophilic enzymes and their importance for food science and technology. In: Handbook of Food Enzymology. (Whitaker, J, Voragen, F., Wong, D. and Beldman, G, Eds.) Chapter 8. pp. 77-100. Marcel Decker, Inc.
- Kristjánsson, M.M. and Magnússon, Ó. Th. (2001) Effect of lyotropic salts on the stability of a subtilisin-like proteinase from a psychrotrophic Vibrio-species, proteinase K and aqualysin I. Protein PeptideLett. 8, 249-255.
- Kristjánsson, M.M., Magnússon, Ó.Þ, Magnússon, H.M., Alfreðsson, G.Á.,. and Matsuzawa, H. (1999) Properties of a subtilisin-like proteinase from a psychrotrophic Vibrio-species. Comparison to proteinase K and aqualysin I. Eur. J. Biochem. 260, 752-760.