Ræder, I.L.U, Paulsen, S.M., Smalås, A.O. and Willassen, N.P. (2007). Effect of fish skin mucus on the soluble proteome of Vibrio salmonicida analysed by 2-D gel electrophoresis and tandem mass spectrometry. Microbial Pathogenesis, 42, 37-46.

Niiranen L., Espelid, S., Karlsen, C.R., Mustonen, M., Paulsen, S.M., Heikinheimo, P. and Willassen, N.P. (2007) Comparative expression study to increase the solubility of cold adapted Vibrio proteins in Escherichia coli, Protein Expression and purification, 52, 210-218.

Riise, E. K., Lorentzen, M. S., Helland, R., Smalås, A.O., Leiros, H-K., and Willassen, N. P. (2007) The first crystal structure of a cold active catalase from Vibrio salmonicida at 1.96 Å reveals structural aspects of cold adaptation. In press, Acta Cryst D.

Sælensminde, G., Halskau jr., Ø., Helland, R., Willassen, N.P., and Jonassen, I. (2007) Structure-dependent relationships between growth temperature of prokaryotes and the amino acid frequency in their proteins. In press, Extremophiles.

Thorvaldsen, S., Hjerde, E., Fenton, C. and Willassen, N.P. (2007) Molecular characterization of cold adaptation based on ortholog protein sequences from Vibrionaceae species. In press, Extremophiles

Smith Tunsjø, H., Paulsen, S.M., Mikkelsen, H., L'Abée-Lund, T., Skjerve, E. and Sørum, Henning. Adaptive response to environmental changes in the fish pathogen Moritella viscose. 2007. In Press, Research in Microbiology.

Altermark, B., Niiranen, L., Willassen, N.P., Smalås, A.O., & Moe, E. (2007) Comparative studies of endonuclease I from cold adapted Vibrio salmonicida and mesophilic Vibrio cholerae. In press, FEBS J.

Larsen, A. F., Moe, E., Helland, R. Gjellesvik, D. R., and Willassen, N. P. (2006) Characterization of a recombinant expressed Proteinase K like enzyme from a psychrotrophic Serratia sp. FEBS J., 273:47-60.

Adekoya, O. A, Willassen, N. P. and Sylte, I. (2006) Molecular insight into pseudolysin inhibition using the MM-PBSA and LIE methods. J. Struct. Biol. J Struct Biol. 153, 129-44.

Helland, R., Larsen, A. F., Smalås, A. O., and Willassen, N. P. (2006) The 1.8 Å crystal structure of a Proteinase K like enzyme from a psychrotroph Serratia species. FEBS J., 273:61-71

Riise, E.K., Lorentzen, M.S., Helland, R. and Willassen, N.P. (2006) Crystallisation and preliminary X-ray diffraction analysis of a cold adapted catalase from Vibrio salmonicida. Acta Cryst. F62, 77-79.

Adekoya, O. A, Helland, R., Willassen, N. P and Sylte, I. (2006) Comparative sequence and structure analysis reveal features of cold adaptation of an enzyme in the thermolysin family. PROTEINS, Structure, Function and Bioinformatics, 62, 435-449.

Lorentzen, M. S., Moe, E., Jouve, H. and Willassen, N.P. (2006) Cold adapted features of Vibrio salmonicida catalase. Characterisation and comparison to the mesophilic counterpart from Proteus mirabilis. Extremophiles, 10, 427-440.

Johansen, R., Nesse, L.L., Gram, L., Willassen, N.P., Sørum, H. (2006) Quorum sensing inhibitorer åpner for muligheter til å bekjempe sykdommer også i akvakultur. Norsk 7/2006, 118:458-462.

Altermark, B., Smalås, A. O., Willassen, N. P. and Helland, R., (2006) The structure of Vibrio cholerae extracellular endonuclease I reveals the presence of a chloride ion completely buried in the protein core. Acta Cryst.,D62, 1387-91.

Peik Haugen, Dawn Simon and Debashish Bhattacharya (2005) The natural history of group I introns. Trends in Genetics, 21:111-119.

Peik Haugen, Odd Gunnar Wikmark, Anna Vader, Dag H. Coucheron, Eva Sjøttem and Steinar Johansen (2005) The recent transfer of a homing endonuclease gene. Nucleic Acids Research, 33:2734-2741.

Adekoya, O.A, Willassen N.P, Sylte, I. (2005) The protein-protein interactions between SMPI and thermolysin studied by molecular dynamics and MM/PBSA calculations. J Biomol Struct Dyn. 22:521-31.

Thorvaldsen, S., Flå, T., and Willassen, N.P. (2005) Extracting molecular diversity between populations through sequence alignments. In Biological and Medical Data Analysis. 6th International symposium ISBMDA 2005, Proceedings Springer verlag. In Press

Eirik W. Lundblad, Peik Haugen and Steinar Johansen (2004) Trans-splicing of mutated glycosylasparaginase mRNA sequences by a group I ribozyme deficient in hydrolysis. European Journal of Biochemistry, 271:4932-4938.

Peik Haugen, Valérie Reeb, François Lutzoni and Debashish Bhattacharya (2004) The evolution of homing endonuclease genes and group I introns in nuclear rDNA. Molecular Biology and Evolution, 21:105-116

Peik Haugen, Henry J. Runge and Debashish Bhattacharya (2004) Long-term evolution of the S788 fungal nuclear small subunit rRNA group I introns. RNA, 10:1084-1096.

Peik Haugen and Debashish Bhattacharya (2004) The spread of LAGLIDADG homing endonuclease genes in rDNA. Nucleic Acids Research, 32:2049-2057.

Peik Haugen, Morten Andreassen, Åsa B. Birgisdottir and Steinar Johansen. (2004) Hydrolytic cleavage by a group I intron ribozyme is dependent on RNA structures not important for splicing. European Journal of Biochemistry, 271:1015-1024.

Leiros, H.K., Brandsdal, B.O., Andersen, O.A., Os, V., Leiros, I, Helland, R., Otlewski, J., Willassen, N.P., Smalas, A.O. (2004) Trypsin specificity as elucidated by LIE calculations, X-ray structures, and association constant measurements. Protein Sci. 13:1056-70.

Moe, E., Leiros I., Riise, E.K., Olufsen, M., Lanes, O, Smalas A. O. and Willassen N.P. (2004) Optimisation of the surface electrostatics as a strategy for cold adaptation of uracil-DNA N-glycosylase (UNG) from Atlantic cod (Gadus morhua). J Mol Biol. 343:1221-30.

Leiros, I., Moe, E., Lanes O., Smalås, A. O., and Willassen, N.P. (2003) The crystal structure of Uracil-DNA glycosylase from Atlantic cod (Gadus morhua) reveals cold-adapted features. Acta Crystallogr D Biol Crystallogr.,59:1357-65.

Peik Haugen, Dag H. Coucheron, Sissel B. Rønning, Kari Haugli and Steinar Johansen (2003) The molecular evolution and structural organization of self-splicing group I introns at position 516 in nuclear SSU rDNA of myxomycetes. The Journal of Eukaryotic Microbiology, 50:283-292.

Henrik Nielsen, Tonje Fiskaa,Åsa B. Birgisdottir, Peik Haugen, Christer Einvik and Steinar Johansen (2003). The ability to form full-length intron RNA circles is a general property of nuclear group I introns. RNA 9:1464-1475.

Lanes, O., Leiros, I., Smalås, A. O., and Willassen, N. P. (2002) Identification, cloning and expression of uracil-DNA glycosylase from Atlantic cod (Gadus morhua). Characterisation and homology modelling of the cold-active catalytic domain. Extremophils 6:73-86

Leiros, I., Lanes, O., Sundheim, O., Helland, R., Smalås, A. O., and Willassen, N.P. (2001) Crystallization and preliminary X-ray diffraction data of a cold-adapted uracil-DNA glycosylase from Atlantic cod (Gadus morhua). Acta Cryst. 57:1706-1708.

Elde, M., Willassen, N.P. and Johansen, S. (2000) Functional characterization of isoschizomeric His-Cys box homing endonucleases from Naegleria. Eur. J. Biochem. 267:1-10.

Lanes, O., Guddal, P. H., Gjellesvik, D. R., and Willassen, N. P. (2000) Purification and characterisation of a cold-adapted Uracil-DNA glycosylase (UNG) from Atlantic cod (Gadus morhua). Comp. Biochem. Biophys. 127:399-410

Smalås, A. O., Os, V., Schrøder, H-K., and Willassen, N. P. (2000) Cold adapted enzymes. Biotechnol Annu Rev. 6:1-57

Schrøder Leiros H. K, Willassen N. P, Smalås A. O. (2000) Structural comparison of psychrophilic and mesophilic trypsins. Elucidating the molecular basis of cold-adaptation. Eur. J. Biochem. 267, 1039-49.

Johnsen, H. K., Tveiten, H., Willassen, N. P. and Arnesen, A.M. (1999) Arctic charr (Salvelinus alpinus) vitellogenin: development and validation of an enzyme-linked immunosorbent assay (ELISA). Comp. Biochem. Biophys. 124, 355-62.

Schrøder, H-K., Willassen, N. P., and Smalås, A. O. (1999) Residue determinants and sequence analysis of cold-adapted trypsins. Extremophiles 3, 205-19.

Elde, M., Haugen, P., Willassen, N. P., and Johansen, S. (1999). I-NjaI, a nuclear intron-encoded homing endonuclease from Naegleria, generates a pentanucleotide 3' cleavage-overhang within a 19 base-pair partially symetric DNA recognition site. Eur. J. Biochem. 259, 281-288.

Helland, R., Berglund, G. I., Otlewski, J., Apostoluk, W., Andersen, O. A., Willassen, N. P., and Smalås, A. O. (1999) High resolution crystal structures of three new trypsin-squach inhibitor complexes. A detatailed comparison with other trypsins and their complexes. Acta Cryst. D55, 139-148.

Helland, R., Leiros, I., Willassen, N. P., Berglund, G. I., and Smalås, A. O. (1998) The crystal structure of anionic salmon trypsin in complex with bovine pancreatic trypsin inhibitor. Eur. J. Biochem. 256, 317-324.

Schrøder, H-K., Willassen, N. P., and Smalås, A. O. (1998) Structure of a non-psychrophilic trypsin form from a cold-adapted fish species. Acta Cryst. D54, 780-798.

Berglund, G. I., Outzen, H., Smalås, A. O. and Willassen, N. P. (1998) Purification and characterization of pancreatic elastase from Atlantic salmon (Salmo salar). Mol. Mar. Biol. Biotechnol. 7, 105-114.

Outzen, H., Berglund, G. I., Smalås, A. O. and Willassen, N. P. (1996) Temperature and pH sensitivity of trypsins from Atlantic salmon (Salmo salar) in comparison with bovine and porcine trypsin. Comp. Biochem. Biophys. 115B, 33-45.

Berglund, G., Willassen, N. P., Hordvik, A. and Smalås, A. O. (1995) Structure of native pancreatic elastase from North Atlantic salmon at 1.61 Å resolution. Acta Cryst., D51, 925-937.

Berglund, G., Smalås, A. O., Hordvik, A. and Willassen, N. P. (1995) Structure of anionic salmon trypsin in a second crystal form. Acta Cryst., D51, 725-730.

Berglund, G., Smalås, A. O., Hansen, L. Kr. and Willassen, N. P. (1995) Crystallisation and preliminary X-ray crystallographic studies of native elastase from North Atlantic salmon (Salmo salar). Acta. Cryst., D51, 393-394.

Smalås, A. O., Heimstad, E. S., Hordvik, A., Willassen, N. P. and Male, R. (1994) Cold-adaption of enzymes: structural comparison between salmon and bovine trypsins. PROTEINS: Structure., Function, and Genetics, 20, 149-166.