| 1. |
- Berggren, K., et al.
(författare)
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Partitioning of peptides and recombinant protein-peptide fusions in thermoseparating aqueous two-phase systems : effect of peptide primary structure
- 2000
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Ingår i: Journal of Chromatography B. - 0378-4347. ; 743:1-2, s. 295-306
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Tidskriftsartikel (refereegranskat)abstract
- Genetic engineering has been used for fusion of peptides, with different length and composition, on a protein to study the effect on partitioning in an aqueous two-phase system. The system was composed of dextran and the thermoseparating ethylene oxide-propylene oxide random copolymer, EO30PO70. Peptides containing tryptophan, proline, arginine or aspartate residues were fused at the C-terminus of the recombinant protein ZZ-cutinase. The aim was to find effective tags for the lipolytic enzyme cutinase for large-scale extraction. The target protein and peptide tags were partitioned separately and then together in the fusion proteins in order to gain increased understanding of the influence of certain amino acid residues on the partitioning. The salt K2SO4 was used to reduce the charge dependent salt effects on partitioning and to evaluate the contribution to the partition coefficient from the hydrophobic-hydrophilic properties of the amino acid residues. The effect of Trp on peptide partitioning was independent of the difference in primary structure for (Trp)n, (Trp-Pro)n, (Ala-Trp-Trp-Pro)n and was only determined by the number of Trp. The effect of the charged residues, Arg and Asp, was dependent on the surrounding residues, i.e. if they were situated next to Trp or not. The partitioning behaviour observed for the peptides was qualitatively and in some cases also quantitatively the same as for the fusion proteins. The effect of the salts sodium perchlorate and triethylammonium phosphate on the partitioning was also studied. The salt effects observed for the peptides were qualitatively similar to the effects observed for the fusion proteins.
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| 2. |
- Fokine, Mikael, et al.
(författare)
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Integrated fiber Mach-Zehnder interferometer for electro-optic switching
- 2002
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 27:18, s. 1643-1645
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Tidskriftsartikel (refereegranskat)abstract
- Molten alloys under high pressure were used to obtain fibers with long internal electrodes that are solid at room temperature. An integrated Mach-Zehnder interferometer was constructed from a twin-core twin-hole fiber that permitted application of an electric field preferentially to one of the cores. Good stability and a switching voltage of 1.4 kV were measured with a 1-m-long fiber device with a quadratic voltage dependence.
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| 3. |
- Gräslund, Torbjörn, et al.
(författare)
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Production of a Thermostable DNA Polymerase by Site-Specific Cleavage of a Heat-Eluted Affinity Fusion Protein
- 1997
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928 .- 1096-0279. ; 9, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- A novel strategy is described for bacterial expression and affinity purification of a recombinant truncated version of the heat-stable DNA polymerase I fromThermus aquaticus.The DNA polymerase ([Delta]Taq) was produced as a fusion to a serum albumin binding affinity handle (ABP) derived from streptococcal protein G. Based on the thermostability of the [Delta]TaqDNA polymerase, affinity-purified ABP-[Delta]Taqcould be heat-eluted from HSA columns by incubation at 85ï¿œC. To produce free [Delta]TaqDNA polymerase, efficient site-specific cleavage of the affinity tag was performed using a recombinant coxsackievirus 3C protease (3Cpro), also produced as an ABP affinity fusion. Thus, an integrated strategy could be devised where both the cleaved ABP affinity tag and the protease fusion could be recovered after site-specific cleavage using HSA-affinity chromatography. The flow-through fraction contained essentially pure [Delta]TaqDNA polymerase with full enzymatic activity.
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| 4. |
- Hjelm, Linnea C., et al.
(författare)
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Lysis of Staphylococcal Cells by Modular Lysin Domains Linked via a n-covalent Barnase-Barstar Interaction Bridge
- 2019
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Bacteriophage endolysins and bacterial exolysins are capable of enzymatic degradation of the cell wall peptidoglycan layer and thus show promise as a new class of antimicrobials. Both exolysins and endolysins often consist of different modules, which are responsible for enzymatic functions and cell wall binding, respectively. Individual modules from different endo- or exolysins with different binding and enzymatic activities, can via gene fusion technology be re-combined into novel variants for investigations of arrangements of potential clinical interest. The aim of this study was to investigate if separately produced cell wall binding and enzyme modules could be assembled into a functional lysin via a non-covalent affinity interaction bridge composed of the barnase ribonuclease from Bacillus amyloliquefaciens and its cognate inhibitor barstar, known to form a stable heterodimeric complex. In a proof-of-principle study, using surface plasmon resonance, flow cytometry and turbidity reduction assays, we show that separately produced modules of a lysin cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) from Staphylococcus aureus bacteriophage K endolysin (LysK) fused to barnase and a cell wall binding Src homology 3 domain (SH3b) from the S. simulans exolysin lysostaphin fused to barstar can be non-covalently assembled into a functional lysin showing both cell wall binding and staphylolytic activity. We hypothesize that the described principle for assembly of functional lysins from separate modules through appended hetero-dimerization domains has a potential for investigations of also other combinations of enzymatically active and cell wall binding domains for desired applications.
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| 5. |
- Kronander, Håkan, 1953-
(författare)
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Diagnostic and Prognostic Value of Exercise Electrocardiographic Test Variables in Coronary Artery Disease
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The diagnostic performance of conventional analysis of the exercise electrocardiographic (ECG) test for the detection of coronary artery disease (CAD) is limited to 70-75%. The exercise ECG test is the most widely used non-invasive method for assessing CAD and even a small improvement in the diagnostic performance is important. The objective of this thesis was to investigate the diagnostic performance of the exercise ECG test for diagnosis of CAD and the prognostic performance of the test for predicting acute myocardial infarction (AMI), in both men and women. In the diagnostic part of the present study, aimed at finding the optimal diagnostic information during the exercise and recovery phase, 1,877 electrocardiograms selected from 8,322 consecutive patients undergoing a routine exercise test on bicycle ergometer were evaluated. CAD was verified angiographically in 669 patients and excluded in 1,208 patients, by angiography (119 patients), by myocardial scintigraphy (250 patients), or on clinical grounds (839 patients). The diagnostic performance of ST-segment amplitude, and the difference between heart rate (HR) matched recovery and exercise ST-segment amplitudes (ST/HR difference), were evaluated by constructing receiver operating characteristic (ROC) curves for each sample point every 12th second during 10 minutes of recovery as well as the last 4 minutes of exercise for the ST-segment amplitude. ST-segment amplitude performed better after exercise than during exercise and best within the first 2 minutes of recovery. Its diagnostic ability did not differ from the ST/HR difference. Both methods performed better in men than in women and the diagnostic information appeared mainly in leads I, -aVR, II, V4, V5 and V6. The effect of different sampling rates (1, 2 and 5 samples/min) on the CAD discrimination ability of ST/HR loop area was evaluated by using ROC curves. A use of sampling frequency below 2 samples/min resulted in a significantly diminished diagnostic performance. ST-segment and ST/HR variables were compared during exercise and during early post-exercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Discriminating capacity of the methods was evaluated by the use of ROC areas. Partition values, providing the combination of the best sensitivity and specificity, were established. The results demonstrate that analysis of post-exercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD. The prognostic part of the study included 8,317 of the 8,322 patients and covered a mean follow-up period of 9.5 years. This part of the study was used to evaluate the long-term prognostic value of ST/HR hysteresis in predicting AMI and all-cause mortality in men and women. ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.
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| 6. |
- Moschetti, Giuseppe, et al.
(författare)
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Planar InAs/AlSb HEMTs With Ion-Implanted Isolation
- 2012
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 33:4, s. 510-512
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Tidskriftsartikel (refereegranskat)abstract
- The fabrication and performance of planar InAs/AlSb high-electron-mobility transistors (HEMTs) based on ion-implantation isolation technology are reported. Ar atoms have been implanted at an energy of 100 keV and with a dose of 2 x 10(15) cm(-2) in order to induce device isolation. The InAs/AlSb HEMT exhibited a maximum drain current of 900 mA/mm, a peak transconductance of 1180 mS/mm, and an f(T)/f(max) ratio of 210 GHz/180 GHz at a low drain bias of 0.3 V. The combination of excellent stability against oxidation with the high device isolation demonstrated by the implantation technique can dramatically improve the suitability of InAs/AlSb HEMTs for high-frequency and ultralow-power MMIC applications.
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| 7. |
- Moschetti, Giuseppe, 1982, et al.
(författare)
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Source-drain scaling of ion-implanted InAs/AlSb HEMTs
- 2012
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Ingår i: Indium Phosphide and Related Materials (IPRM), 2012 International Conference on. - : IEEE. - 1092-8669. - 9781467317252 ; , s. 57-60
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Konferensbidrag (refereegranskat)abstract
- We report on the lateral scaling of true planar InAs/AlSb high electron mobility transistors (HEMTs) based on ion implantation for device isolation. When reducing the source drain distance, dsd, from 2.5 μm to 1 μm, the HEMTs showed up to 56% higher maximum drain current, 23% higher peak transconductance and T of 185 GHz (+32%). A trade-off in the lateral scaling is needed due to increased gate leakage current and pinch-off degradation for dsd below 1.5 μm. The ability to withstand oxidation of the InAs/AlSb heterostructure makes the planar technology based on ion implantation extremely promising for MMIC integration of InAs/AlSb HEMTs.
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| 8. |
- Moschetti, Giuseppe, 1982, et al.
(författare)
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True planar InAs/AlSb HEMTs with ion-implantation technique for low-power cryogenic applications
- 2013
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 79, s. 268-273
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the room-temperature and cryogenic properties of true planar 110 nm InAs/AlSb HEMTs fabricated with Ar-ion isolation technology. Device isolation is generally improved and is in particular increased by four orders of magnitude at 6 K compared to 300 K. This results in improved drain current saturation, lower gate leakage current and 23% higher peak transconductance. The RF performance is significantly improved as well, with 47% higher f(T) (162 GHz) and 72% higher f(max) (155 GHz) at the low drain voltage of 0.1 V, compared to room temperature. The overall performance of the fabricated devices shows the suitability of ion implantation for the device isolation at cryogenic temperature. Furthermore, the excellent stability against oxidation and truly planar structure of these devices demonstrate great potential for highly integrated cryogenic millimeter-wave circuits in InAs/AlSb technology with ultra-low power consumption.
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| 9. |
- Neiman, Maja, et al.
(författare)
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Selectivity analysis of single binder assays used in plasma protein profiling
- 2013
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Ingår i: Proteomics. - : Wiley. - 1615-9853 .- 1615-9861. ; 13:23-24, s. 3406-3410
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Tidskriftsartikel (refereegranskat)abstract
- The increasing availability of antibodies toward human proteins enables broad explorations of the proteomic landscape in cells, tissues, and body fluids. This includes assays with antibody suspension bead arrays that generate protein profiles of plasma samples by flow cytometer analysis. However, antibody selectivity is context dependent so it is necessary to corroborate on-target detection over off-target binding. To address this, we describe a concept to directly verify interactions from antibody-coupled beads by analysis of their eluates by Western blots and MS. We demonstrate selective antibody binding in complex samples with antibodies toward a set of chosen proteins with different abundance in plasma and serum, and illustrate the need to adjust sample and bead concentrations accordingly. The presented approach will serve as an important tool for resolving differential protein profiles from antibody arrays within plasma biomarker discoveries.
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| 10. |
- Neiman, Maja, et al.
(författare)
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Validating the selectivity of antibodies used in multiplexed serum profiling via parallel immunocapture analysis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The increasing availability of antibodies towards human proteins drives the generation of new and exploratory data, which can be generated by profiling e.g. plasma samples using multiplexed arrays. However, antibody assays can lead to erroneous results due to cross-‐reactivity to off-‐targets. Here, we describe an approach in which an antibody-‐based suspension bead array is combined with subsequent validation of on-‐ target binding using a coupled affinity purification assay. Based on differential heat treatment of samples, antibody performance was investigated and the results for antibodies directed towards several complement factors provide insights on the detection of proteins in sera from patients with complement deficiency. In conclusion, the combined parallel flow and blot based immunocapture analysis serves an important, first line tool for resolving differently detected serum or plasma protein profiles proposed by antibody arrays.
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