Johan Sjödahl
Royal Institute of Technology
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Publication
Featured researches published by Johan Sjödahl.
Journal of Micromechanics and Microengineering | 2002
Patrick Griss; Jessica Melin; Johan Sjödahl; Johan Roeraade; Göran Stemme
Two novel types of micromachined nanoelectrospray emitter tips have been designed, fabricated and tested. The fabrication method of the hollow tips is based on a self-aligning deep reactive ion etch process. The tips consist of either silicon dioxide or silicon and feature orifice diameters of 10 and 18 μm, respectively. The geometrical characteristics of both emitter types are favorable for the generation of stable electrospray ionization, i.e. wetting of the tip shaft is avoided and the base of the Taylor cone is limited to the diameter of the orifice. A silicon dioxide tip was operated in a bench top setup to visually evaluate the electrospray. Both types of tips were also successfully used for the analysis of an insulin sample in an ion trap mass spectrometer.
Protein Expression and Purification | 2002
Johan Sjödahl; Åsa Emmer; Jan Vincent; Johan Roeraade
Fractions of three trypsin-like proteinases, TL I, TL II, and TL III, a chymotrypsin-like proteinase, CL, two carboxypeptidase A enzymes, CPA I and CPA II and two carboxypeptidase B enzymes, CPB I and CPB II, from Antarctic krill (Euphausia superba) have been characterized with respect to purity by the means of capillary electrophoresis, CE, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The masses of the trypsin-like and chymotrypsin-like proteinases were determined to be 25,020, 25,070, 25,060, and 26,260Da for TL I, TL II, TL III, and CL, respectively. The masses of the CPA enzymes are likely 23,170 and 23,260Da, whereas the CPB enzyme masses likely are 33,730 and 33,900Da. The degradation efficiency and cleavage pattern of the trypsin-like proteinases were studied with native myoglobin as a model substrate using CE, MALDI-TOF-MS, and nanoelectrospray mass spectrometry (nESI-MS). The degradation efficiency of the trypsin-like proteinases was found to be approximately 12 and 60 times higher compared to bovine trypsin at 37 degrees C and 1-3 degrees C, respectively. All three fractions of trypsin-like proteinases showed a carboxypeptidase activity in combination with their trypsin activity.
Journal of Chromatography B: Biomedical Sciences and Applications | 1998
Johan Sjödahl; Åsa Emmer; Björn Karlstam; Jan Vincent; Johan Roeraade
Extracts prepared from Antarctic krill (Euphausia superba), mainly consisting of acidic proteolytic enzymes, have been studied with capillary electrophoretic techniques. Approximately 50 repeatable peaks were obtained with capillary zone electrophoresis on an untreated fused-silica capillary using a phosphate buffer containing anionic and cationic fluorosurfactant additives as separation medium. A faster separation was achieved on a polyvinyl alcohol coated capillary. Quantitative variations of individual proteins regarding different krill enzyme batches were noted. In the krill samples trypsin-like serine proteinase, carboxypeptidase A and carboxypeptidase B were tentatively identified.
Rapid Communications in Mass Spectrometry | 2003
Johan Sjödahl; Jessica Melin; Patrick Griss; Åsa Emmer; Göran Stemme; Johan Roeraade
Rapid Communications in Mass Spectrometry | 2004
Martin Kempka; Johan Sjödahl; Anders Björk; Johan Roeraade
Analytical and Bioanalytical Chemistry | 2009
Michael Hartmann; Johan Sjödahl; Mårten Stjernström; Johan Pettersson Redeby; Thomas O. Joos; Johan Roeraade
Langmuir | 2007
Walter Villanueva; Johan Sjödahl; Mårten Stjernström; Johan Roeraade; Gustav Amberg
Analytical Chemistry | 2005
Johan Sjödahl; Martin Kempka; Karin Hermansson; and Anders Thorsén; Johan Roeraade
Rapid Communications in Mass Spectrometry | 2006
Patrik Ek; Johan Sjödahl; Johan Roeraade
Langmuir | 2006
Suguru Uemura; Mårten Stjernström; Johan Sjödahl; Johan Roeraade