| 1. |
- Grubb, A
(author)
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Analysis of the immunochemical relationship between antigens by electrophoresis in agarose gels containing antibodies
- 1972
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In: Scandinavian journal of clinical and laboratory investigation. Supplementum. - : Informa UK Limited. - 0085-591X .- 0036-5513 .- 1502-7686. ; 124, s. 59-65
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Journal article (peer-reviewed)abstract
- A procedure is described, in which two antigens are brought to interact during their electrophoretic migration in an agarose gel containing antiserum. Three fundamental precipitation patterns can be discerned. These patterns correspond to the three basic precipitation patterns obtained with the double radial immunodiffusion procedure of Ouchterlony. The procedure described here can thus be used in the analysis of the immunochemical relationsship between antigens. It may also be used for estimating the percentage of cross-reacting antibodies in an antiserum. The procedure requires only a few hours.
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| 2. |
- Hillarp, A
(author)
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Molecular analysis of the beta-chain of human C4b-binding protein
- 1991
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In: Scandinavian journal of clinical and laboratory investigation. Supplementum. - : Informa UK Limited. - 0085-591X .- 0036-5513 .- 1502-7686. ; 204, s. 57-69
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Research review (peer-reviewed)abstract
- C4b-binding protein (C4BP) is a multimeric glycoprotein in plasma with important regulatory functions in the complement system. It occurs in two forms, as free protein and in a non-covalent bimolecular complex with the vitamin K-dependent protein S. Protein S is an important anticoagulant and enhances the rate of inactivation by activated protein C of blood coagulation factors, Va and VIIIa. Protein S bound to C4BP is inactive as an anticoagulant, indicating C4BP to have a regulatory function in the blood coagulation process. Approximately 50% of C4BP in plasma circulates in complex with protein S, but little has been known about as to how these proteins interact. This report describes the structure of C4BP and its relation to protein S binding. A novel C4BP subunit, designated the beta-chain, which in all likelihood contains the protein S binding site, has been identified, isolated and characterized. The major form of C4BP is composed of seven alpha-chains and one beta-chain, and the subunits are covalently linked by their carboxy-terminal regions giving the molecule a spider-like quaternary structure. A subpopulation of C4BP, which does not bind protein S, was found to lack the beta-chain. This provides support for the concept that the single protein S binding site is located on the beta-chain. The beta-chain is structurally related to the alpha-chain of C4BP, and both subunits belong to the superfamily of C3b/C4b-binding proteins. The genes coding for the alpha- and beta-chains of C4BP were found to be closely linked within a cluster of genes, coding for structurally related proteins, on the long arm of human chromosome 1.
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| 3. |
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| 4. |
- Persson, Kristina
(author)
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Role of the N-terminal EGF module of coagulation factor IX in activation of factors IX and X.
- 2002
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In: Scandinavian journal of clinical and laboratory investigation. - : Informa UK Limited. - 0085-591X .- 0036-5513 .- 1502-7686. ; 62:Suppl 237, s. 13-18
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Journal article (peer-reviewed)abstract
- Absence or reduced activity of coagulation factor IX (FIX) causes the severe bleeding disorder haemophilia B. FIX contains a Gla module, two epidermal growth factor-like (EGF) modules, and a serine protease region. I characterized a monoclonal antibody and found that it recognizes an epitope around residues 72 and 80 in the C-terminal part of EGF1 in human FIX. The antibody exhibited 10-fold greater affinity for activated FIX (FIXa) than for the zymogen FIX, indicating the existence of intra-molecular communication between the serine protease region and EGF1. Binding of the antibody did not affect the amidolytic activity of FIXa, hence I could use the antibody during activation of FIX to show that the C-terminal part of EGF1 is of importance for the interaction with FXIa but not with FVIIa/TF. Considering activation of FX, it is a matter of debate whether EGF1 or FIXa interacts directly with FVIIIa. I activated FX in the presence and absence of the antibody and/or FVIIIa. The addition of antibody caused only a minor decrease in k cat,app , and the major increase in k cat,app caused by the addition of FVIIIa occurred even in the presence of the antibody. This implies that EGF1 of FIXa is not directly involved in interaction with FVIIIa in the Xase complex. A model of the FIXa-FVIIIa complex, based on my findings and results from the literature, was constructed and indicated that EGF1 of FIXa does not interact directly with FVIIIa.
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| 5. |
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| 6. |
- Steen, Mårten
(author)
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Factor Va-factor Xa interactions: molecular sites involved in enzyme:cofactor assembly.
- 2002
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In: Scandinavian journal of clinical and laboratory investigation. - : Informa UK Limited. - 0085-591X .- 0036-5513 .- 1502-7686. ; 62:Suppl 237, s. 5-11
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Journal article (peer-reviewed)abstract
- The generation of thrombin by the prothrombinase complex is a key event in coagulation. In this complex, the activated form of coagulation factor V (FVa) serves as an essential cofactor to factor Xa (FXa) in the activation of prothrombin to thrombin. The enzyme FXa is virtually ineffective in the absence of its cofactor. The assembly of FXa with its cofactor FVa on negatively charged phospholipid membranes enhances its catalytic efficiency by several orders of magnitude. The non-activated procofactor factor V (FV) circulates in plasma with a domain organization of A1-A2-B-A3-C1-C2 expressing little procoagulant activity. Upon activation through limited proteolysis by either thrombin or FXa, the B-domain dissociates from FVa. After activation, the procoagulant activity of FVa is greatly enhanced. This report provides insight into the interaction of FV and FXa and the molecular events important in enzyme:cofactor assembly of the FXa:FVa complex. Furthermore, light is shed on the molecular events associated with the activation process, i.e. the release of the B-domain and exposure of binding sites for FXa. The assembly of FVa and FXa was studied using a set of recombinant FV mutants. The interaction between FVa and FXa on phospholipid was investigated with a functional prothrombin activation assay as well as in a novel direct binding assay in the absence of prothrombin. We found that all three thrombin cleavages in FV contribute to increasing the FXa affinity and that the B-domain in intact FV has an inhibitory effect on the FV-FXa interaction, which is important in prohibiting premature coagulation.
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| 7. |
- Webb, Joanna
(author)
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Studies on the interaction between vitamin K-dependent protein S and complement regulator C4b-binding protein: localization of binding sites and identification of a possible function of the complex.
- 2002
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In: Scandinavian journal of clinical and laboratory investigation. - : Informa UK Limited. - 0085-591X .- 0036-5513 .- 1502-7686. ; 62:Suppl 237, s. 19-28
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Journal article (peer-reviewed)abstract
- Complement is a cascade-like system that is part of the innate immune defence. It is an explosive system, potentially harmful also for the host cells, and needs to be strictly regulated. An important down-regulator of complement is C4b-binding protein (C4BP). C4BP contains two different types of subunits, seven identical a-chains and one unique P-chain. The alpha-chains bind to C4b, C4BP's target in the complement system. The P-chain binds to vitamin K-dependent protein S. Approximately 70% of all protein S in plasma circulates in a high affinity complex with C4BP. Free protein S, the remaining 30%, functions as an important cofactor in the anticoagulant system. The reason for the complex formation between C413P and protein S has remained an intriguing enigma. Protein S has a very high affinity to negatively charged phospholipids for protein S. One area where such phospholipids are present is the surface of the apoptotic cell, where the exposure of phosphatidylserine is an early event. Physiological apoptosis is characterized by a lack of inflammatory response in surrounding tissues, indicating that cells are rapidly cleared before leaking cytoplasmic components into the extracellular space. A number of studies demonstrate that early complement proteins are important for the removal of apoptotic cells, but that subsequent assembly of later complement components and anaphylatoxin release must be prohibited in order not to provoke an inflammatory response. We demonstrate that protein S localizes C4BP to the surface of apoptotic cells via binding to the exposed phosphatidylserine. The C4BP attached to the apoptotic cell through protein S was still able to bind C4b, suggesting that C413P retains its physiological function also when localized to the apoptotic cell surface. In addition, we have also pinpointed a hydrophobic binding site for protein S on C4BP. The binding studies between C413P and protein S were performed on recombinant proteins where mutations had been introduced. Mutations were chosen based on a 3D-homology model of the C4BP P-chain.
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| 8. |
- Peura, Sari, et al.
(author)
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Normal values for calprotectin in stool samples of infants from the population-based longitudinal born into life study
- 2018
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In: Scandinavian Journal of Clinical and Laboratory Investigation. - Stockholm : Taylor & Francis Group. - 0036-5513 .- 1502-7686. ; 78:1-2, s. 120-124
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Journal article (peer-reviewed)abstract
- Faecal calprotectin is a protein used as a diagnostic marker for inflammatory bowel diseases. We determined upper limits for normal calprotectin values for neonatal, 6, 12 and 24 months old children using a turbidimetric immunoassay in a cohort of Swedish children. The advantage of the method is that opposite to previously used enzyme-linked immunosorbent assay (ELISA) method, it enables measuring single samples, and thus, shortens the analysis time significantly. There were 72 samples (41.7% female) collected neonatally, 63 samples (34.9% female) at 6 months, 60 samples (40.0% female) at 12 months and 51 samples (43.1% female) at 24 months. The upper limits for normal values were 233, 615, 136 and 57 µg mg-1 for infants aged 0, 6, 12 and 24 months, respectively.
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