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- Behravan, G, et al.
(författare)
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Expression, purification and characterization of the homeodomain of rat ISL-1 protein.
- 1997
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Ingår i: Protein Engineering. - 0269-2139 .- 1460-213X. ; 10:11, s. 1327-31
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Tidskriftsartikel (refereegranskat)abstract
- Isl-1 is a member of a family of Homeodomains containing proteins that possess an N-terminal pair of zinc binding LIM domains. The Isl-1 gene in rat codes for a protein that binds to the insulin gene enhancer and is also involved in regulation of amylin and proglucagon genes. A DNA sequence coding for 66 amino acid residues containing the C-terminal homeodomain fragment of Isl-1 was expressed as a soluble protein in Escherichia coli. Here, we describe a procedure which allows the rapid native purification of recombinant homeodomain protein fused to an N-terminal tag of six histidines. The purified homeodomain showed DNA-binding activity to its cognate DNA sequence. An enhanced binding activity is observed in the presence of a reducing agent in electrophoretic mobility shift assays. The DNA binding was further characterized by circular dichroism spectroscopy. Addition of DNA to the homeodomain did not change the overall secondary structure content, but the thermal and chemical denaturing profiles were altered. A stabilization of the secondary structure was observed upon DNA binding. The free energy of unfolding at 23 degrees C was 7 kJ mol(-1) in absence of DNA and 29 kJ mol(-1) in the presence of DNA.
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| 4. |
- Chaga, Grigoriy, et al.
(författare)
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Engineering of a metal coordinating site into human glutathione transferase M1-1 based on immobilized metal ion affinity chromatography of homologous rat enzymes
- 1994
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Ingår i: Protein Engineering. - : Oxford University Press (OUP). - 0269-2139 .- 1460-213X. ; 7:9, s. 1115-1119
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Tidskriftsartikel (refereegranskat)abstract
- Rat glutathione transferase (GST) 3-3 binds to Ni(II)-iminodiacetic acid (IDA)-agarose, whereas other GSTs that are abundant in rat liver do not bind to this immobilized metal ion affinity chromatography (IMAC) adsorbent. Rat GST 3-3 contains two superficially located amino acid residues, His84 and His85, that are suitably positioned for coordination to Ni(II)-IDA-agarose. This particular structural motif is lacking in GSTs that do not bind to the IMAC matrix. Creation of an equivalent His-His structure in the homologous human GST M1-1 by protein engineering afforded a mutant enzyme that displays affinity for Ni(II)-IDA-agarose, in contrast to the wild-type GST M1-1. The results identify a distinct site that is operational in IMAC and suggest an approach to the rational design of novel integral metal coordination sites in proteins.
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| 7. |
- Gräslund, Torbjörn, et al.
(författare)
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Charge engineering of a protein domain to allow efficient ion-exchange recovery
- 2000
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Ingår i: Protein Engineering. - : Oxford University Press (OUP). - 0269-2139 .- 1460-213X. ; 13:10, s. 703-709
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Tidskriftsartikel (refereegranskat)abstract
- We have created protein domains with extreme surface charge. These mutated domains allow for ion-exchange chromatography under conditions favourable for selective and efficient capture, using Escherichia coli as a host organism. The staphylococcal protein A-derived domain Z (Z(wt)) was used asa scaffold when constructing two mutants, Z(basic1) and Z(basic2), with high positive surface charge. Far-ultraviolet circular dichroism measurements showed that they have a secondary structure content comparable to the parental molecule Z(wt). Although melting temperatures (T-m) of the engineered domains were lower than that of the wild-type Z domain, both mutants could be produced successfully as intracellular full-length products in E. coli and purified to homogeneity by ion-exchange chromatography. Further studies performed on Z(basic1) and Z(basic2) showed that they were able to bind to a cation exchanger even at pH values in the 9 to 11 range. A gene fusion between Z(basic2) and the acidic human serum albumin binding domain (ABD), derived from streptococcal protein G, was also constructed. The gene product Z(basic2)-ABD could be purified using cation-exchange chromatography from a whole cell lysate to more than 90% purity.
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| 8. |
- Gulich, S., et al.
(författare)
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Engineering streptococcal protein G for increased alkaline stability
- 2002
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Ingår i: Protein Engineering. - : Oxford University Press (OUP). - 0269-2139 .- 1460-213X. ; 15:10, s. 835-842
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Tidskriftsartikel (refereegranskat)abstract
- Most protein-based affinity chromatography media are very sensitive towards alkaline treatment, which is a preferred method for regeneration and removal of contaminants from the purification devices in industrial applications. In a previous study, we concluded that a simple and straightforward strategy consisting of replacing asparagine residues could improve the stability towards alkaline conditions. In this study, we have shown the potential of this rationale by stabilizing an IgG-binding domain of streptococcal protein G, i.e. the C2 domain. In order to analyze the contribution of the different amino acids to the alkaline sensitivity of the domain we used a single point mutation strategy. Amino acids known to be susceptible towards high pH, asparagine and glutamine, were substituted for less-alkali-susceptible residues. In addition, aspartic acid residues were mutated to evaluate if the stability could be further increased. The stability of the different C2 variants was subsequently analyzed by exposing them to NaOH. The obtained results reveal that the most sensitive amino acid towards alkaline conditions in the structure of C2 is Asn36. The double mutant, C2(N7,36A), was found to be the most stable mutant constructed. In addition to the increased alkaline stability and also very important for potential use as an affinity ligand, this mutated variant also retains the secondary structure, as well as the affinity to the Fc fragment of IgG.
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| 9. |
- Gustavsson, M., et al.
(författare)
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Stable linker peptides for a cellulose-binding domain-lipase fusion protein expressed in Pichia pastoris
- 2001
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Ingår i: Protein Engineering. - : Oxford University Press (OUP). - 0269-2139 .- 1460-213X. ; 14:9, s. 711-715
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Tidskriftsartikel (refereegranskat)abstract
- Fusion proteins composed of a cellulose-binding domain from Neocallimastix patriciarum cellulase A and Candida antarctica lipase B were constructed using different linker peptides. The aim was to create proteolytically stable linkers that were able to join the functional modules without disrupting their function. Six fusion variants containing linkers of 4-44 residues were expressed in Pichia pastoris and analysed. Three variants were found to be stable throughout 7-day cultivations. The cellulose-binding capacities of fusion proteins containing short linkers were slightly lower compared with those containing long linkers. The lipase-specific activities of all variants, in solution or immobilized on to cellulose, were equal to that of the wildtype lipase.
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