| 1. |
- Carlsson, Karin, 1975-, et al.
(författare)
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Inhibitors of factor VIIa affect the interface between the protease domain and tissue factor
- 2006
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 349:3, s. 1111-1116
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Tidskriftsartikel (refereegranskat)abstract
- Blood coagulation is triggered by the formation of a complex between factor VIIa (FVIIa) and its cofactor, tissue factor (TF). The γ-carboxyglutamic acid-rich domain of FVIIa docks with the C-terminal domain of TF, the EGF1 domain of FVIIa contacts both domains of TF, and the EGF2 domain and protease domain (PD) form a continuous surface that sits on the N-terminal domain of TF. Our aim was to investigate the conformational changes that occur in the sTF·PD binding region when different types of inhibitors, i.e., one active-site inhibitor (FFR-chloromethyl ketone (FFR)), two different peptide exosite inhibitors (E-76 and A-183), and the natural inhibitor tissue factor pathway inhibitor (TFPI), were allowed to bind to FVIIa. For this purpose, we constructed two sTF mutants (Q37C and E91C). By the aid of site-directed labeling technique, a fluorescent label was attached to the free cysteine. The sTF·PD interface was affected in position 37 by the binding of FFR, TFPI, and E-76, i.e., a more compact structure was sensed by the probe, while for position 91 located in the same region no change in the surrounding structure was observed. Thus, the active site inhibitors FFR and TFPI, and the exosite inhibitor E-76 have similar effects on the probe in position 37 of sTF, despite their differences in size and inhibition mechanism. The allosteric changes at the active site caused by binding of the exosite inhibitor E-76 in turn induce similar conformational changes in the sTF·PD interface as does the binding of the active site inhibitors. A-183, on the other hand, did not affect position 37 in sTF, indicating that the A-183 inhibition mechanism is different from that of E-76.
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| 2. |
- Andersson, D., et al.
(författare)
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Cofactor-induced refolding : Refolding of molten globule carbonic anhydrase induced by Zn(II) and Co(II)
- 2001
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 40:9, s. 2653-2661
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Tidskriftsartikel (refereegranskat)abstract
- The stability versus unfolding to the molten globule intermediate of bovine carbonic anhydrase II (BCA II) in guanidine hydrochloride (GuHCl) was found to depend on the metal ion cofactor [Zn(II) or Co(II)], and the apoenzyme was observed to be least stable. Therefore, it was possible to find a denaturant concentration (1.2 M GuHCl) at which refolding from the molten globule to the native state could be initiated merely by adding the metal ion to the apo molten globule. Thus, refolding could be performed without changing the concentration of the denaturant. The molten globule intermediate of BCA II could still bind the metal cofactor. Cofactor-effected refolding from the molten globule to the native state can be summarized as follows: (1) initially, the metal ion binds to the molten globule, (2) compaction of the metal-binding site region is then induced by the metal ion binding, (3) a functioning active center is formed, and (4) finally, the native tertiary structure is generated in the outer parts of the protein.
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| 3. |
- Borén, Kristina, et al.
(författare)
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Rapid ion-exchange chromatography for preparative separation of proteins IV. Application to bovine carbonic anhydrase III from skeletal muscle
- 1991
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 588:1-2, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Bovine muscle carbonic anhydrase III was purified to homogeneity by the strategy of rapid ion-exchange chromatography. The ionic exchanger used was CM-cellulose, and this is the first application of this technique on a cation exchanger. Nitrogen gas was used to pressurize the chromatographic column to accelerate the elution. The results show that proteins with high isoelectric points can also be purified in this way. The procedure is very time-saving compared with conventional chromatography, reducing the elution time five-to ten-fold. The proteins are in addition protected against oxidation by air.
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| 4. |
- Hammarström, Per, 1972-, et al.
(författare)
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Is the unfolded state the Rosetta Stone of the protein folding problem?
- 2000
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 276:2, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- Solving the protein folding problem is one of the most challenging tasks in the post genomic era. Identification of folding-initiation sites is very important in order to understand the protein folding mechanism. Detection of residual structure in unfolded proteins can yield important clues to the initiation sites in protein folding. A substantial number of studied proteins possess residual structure in hydrophobic regions clustered together in the protein core. These stable structures can work as seeds in the folding process. In addition, local preferences for secondary structure in the form of turns for ▀-sheet initiation and helical turns for a-helix formation can guide the folding reaction. In this respect the unfolded states, studied at increasing structural resolution, can be the Rosetta Stone of the protein folding problem. (C) 2000 Academic Press.
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| 5. |
- Hammarström, Per, 1972-, et al.
(författare)
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Protein substrate binding induces conformational changes in the chaperonin GroEL : A suggested mechanism for unfoldase activity
- 2000
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 275:30, s. 22832-22838
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Tidskriftsartikel (refereegranskat)abstract
- Chaperonins are molecules that assist proteins during folding and protect them from irreversible aggregation. We studied the chaperonin GroEL and its interaction with the enzyme human carbonic anhydrase II (HCA II), which induces unfolding of the enzyme. We focused on conformational changes that occur in GroEL during formation of the GroEL-HCA II complex. We measured the rate of GroEL cysteine reactivity toward iodo[2-(14)C]acetic acid and found that the cysteines become more accessible during binding of a cysteine free mutant of HCA II. Spin labeling of GroEL with N-(1-oxy1-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide revealed that this additional binding occurred because buried cysteine residues become accessible during HCA II binding. In addition, a GroEL variant labeled with 6-iodoacetamidofluorescein exhibited decreased fluorescence anisotropy upon HCA II binding, which resembles the effect of GroES/ATP binding. Furthermore, by producing cysteine-modified GroEL with the spin label N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide and the fluorescent label 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid, we detected increases in spin-label mobility and fluorescence intensity in GroEL upon HCA II binding. Together, these results show that conformational changes occur in the chaperonin as a consequence of protein substrate binding. Together with previous results on the unfoldase activity of GroEL, we suggest that the chaperonin opens up as the substrate protein binds. This opening mechanism may induce stretching of the protein, which would account for reported unfoldase activity of GroEL and might explain how GroEL can actively chaperone proteins larger than HCA II.
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| 6. |
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| 7. |
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| 8. |
- Karlsson, Martin, 1965-, et al.
(författare)
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Adsorption at the liquid-solid Interface - Influence of protein stability on conformational changes
- 2007. - 2
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Ingår i: Encyclopedia of surfaces and colloid science. - : Taylor & Francis. - 9780849396090
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Bokkapitel (refereegranskat)abstract
- Protein adsorption has large implications in a variety of fields and can be both a problem and an asset. Most often protein adsorption is accompanied by structural changes in the adsorbed protein. The degree and rate of these changes are dependent on the surface, conditions during adsorption and experimental set up as well as of intrinsic properties of the protein. The effect of conformational changes influences both practical applications and experimental results in studies of protein adsorption at the liquid/solid interface. The intrinsic property of the protein that is most instrumental for conformational changes upon adsorption is the stability of the protein. Hence, large efforts have been directed towards analysis of how both the nature of surfaces and conditions influence the stability of proteins upon adsorption. Less work has been focused on the reversed view, i.e. how the stability of proteins influences adsorption, the rate and degree of the subsequent conformational changes as well as the effects of these changes. However, the increasing use of proteins in a variety of medical and biotechnological applications requires a deeper knowledge of the importance and effects of stabilizing interactions in the protein structure. Engineered stabilized proteins that are less affected by surface interactions should be of potential use for various practical purposes.
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| 9. |
- Karlsson, Martin, 1965-, et al.
(författare)
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Protein adsorption orientation in the light of fluorescent probes : mapping of the interaction between site-directly labeled human carbonic anhydrase II and silica nanoparticles
- 2005
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 88:5, s. 3536-3544
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the direction and specificity of protein adsorption to solid surfaces, a knowledge that is of great importance in many biotechnological applications. To resolve the direction in which a protein with known structure and surface potentials binds to negatively charged silica nanoparticles, fluorescent probes were attached to different areas on the surface of the protein human carbonic anhydrase II. By this approach it was clearly demonstrated that the adsorption of the native protein is specific to limited regions at the surface of the N-terminal domain of the protein. Furthermore, the adsorption direction is strongly pH-dependent. At pH 6.3, a histidine-rich area around position 10 is the dominating adsorption region. At higher pH values, when the histidines in this area are deprotonated, the protein is also adsorbed by a region close to position 37, which contains several lysines and arginines. Clearly the adsorption is directed by positively charged areas on the protein surface toward the negatively charged silica surface at conditions when specific binding occurs.
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| 10. |
- Knudsen, J.F., et al.
(författare)
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The cyclooxygenase-2 inhibitor celecoxib is a potent inhibitor of human carbonic anhydrase II
- 2004
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Ingår i: Inflammation. - : Springer Science and Business Media LLC. - 0360-3997 .- 1573-2576. ; 28:5, s. 285-290
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Tidskriftsartikel (refereegranskat)abstract
- Cyclooxygenase-2 (COX-2) is up-regulated in stromal and inflammatory cells. The inducible COX-2 isoform is expressed during inflammation, in some cancers, and in brain tissue after global and focal ischemia. Tissue acidosis is a dominant factor in inflammation, and contributes to pain and hyperalgesia. Recently, compelling epidemiological and clinical evidence has documented the COX-independent effects of some COX-2 inhibitors (i.e., celecoxib, valdecoxib, and rofecoxib), among these effects are carbonic anhydrase (CA) inhibition. Carbonic anhydrases are zinc metalloenzymes expressed in various cell types, including those of the kidney, where they act as general acid-base catalysts. The kidneys are also known to express the highest concentration of COX-2 messenger ribonucleic acid. Celecoxib, like the prototypic CA inhibitor acetazolamide, is structurally characterized by an unsubstituted sulfonamide moiety. In the present study, we report that celecoxib exhibits the characteristics of a potent CA inhibitor, showing inhibitory human carbonic anhydrase II (hCAII) activity in the nanomolar range. Valdecoxib was relatively less potent. Rofecoxib, which lacks the unsubstituted sulfonamide moiety characteristic of CA inhibitors, showed no significant hCAII inhibitory activity. The current study corroborates our earlier report of structure-activity relationships as predictors of such metabolic events as hyperchloremia, acidosis, and changes in calcium and phosphate disposition, and clinical manifestations associated with CA inhibition reported with celecoxib. These data showing inhibition of hCAII by the unsubstituted sulfonamides celecoxib and valdecoxib, but not by rofecoxib, may have important implications for the elucidation of the mechanisms of action as well as the side effects associated with COX-2 inhibitors. © 2004 Springer Science+Business Media, Inc.
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