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Biomedical subjects

U Hamberg

Publications and source records attributed to U Hamberg.

At least 19 recordsLinked to original sources
PubMed1984

Determination of human plasma kininogen by a single radial immunodiffusion method and the bradykinin equivalent.

An SRI method is presented for the quantitation of native human plasma kininogen using a monospecific high avidity antiserum prepared against the conformational determinants of kininogen heavy chain (HC antigen). The SRI value of total human plasma kininogen averaged 0.260 +/- 0.052 g/l (+/- 2 SD) using a standard curve of normal human plasma in each assay (measuring range 0.016-0.260 g/l). The SRI data, confirmed by RIA, were compared with determination of the bradykinin equivalent by bioassay 4.30 +/- 0.052 mg/l (+/- 2 SD), generally accepted as a measure of total plasma kininogen. The SRI method does not discriminate between LMr and HMr kininogen but detects an increase of total kininogen independently of bradykinin release as a consequence of activated proteolysis. It is suggested that the SRI method can be applied to study levels of kininogen in clinical research.

Animals↗
PubMed1983

Conformation and sequence dependent antigenic determinants in human low molecular weight kininogen.

Conformation and sequence-dependent antigenic determinants were investigated using a kinin-free low molecular weight kininogen isolated from Cohn's plasma fraction IV. This antigen contains the determinants of the apparently intact heavy chain common to the high molecular weight and low molecular weight kininogens. Straightforward reduction and carboxymethylation destroyed the immunoreactivity of this molecule. Antiserum prepared against the reduced protein recognized both reduced and unreduced antigen showing the presence of both types of antigenic determinant. The corresponding antibodies were separated using immunoadsorbent columns. As shown by the higher avidity of the antibodies, the conformation-dependent determinants dominate the antigenic structure.

Amino Acids↗
PubMed1982

Isolation and immunologic properties of a heterogeneous antigen with the characteristics of the heavy chain of human plasma kininogen.

Kininogen antigen was purified from human plasma fraction IV by ion exchange chromatography, gel filtration and affinity chromatography with antibody specific immunoadsorbents. The immunologically pure glycoprotein had a mol. wt of approximately 60,000 and only one polypeptide chain by SDS-PAGE. An extensive charge heterogeneity by isoelectric focusing and gel filtration on polyacrylamide agarose could only in part depend on a comparatively high sialic acid content, but may be caused by differences in the carbohydrate structures sustained by lectin-binding heterogeneity on Con A-Sepharose. This antigen shares a dominating determinant with native plasma kininogens shown by complete patterns of identity in immunochemical analyses and with the monospecific antisera developed in rabbits against the heterogeneous components. The similar size, amino acid composition, low histidine content, lack of N-terminal amino acid and antigenic homogeneity fit all the so far known characteristics of the human kininogen heavy chain. Notably the antigenic determinant is resistant to degradation by activated kallikrein. This antigen with unimpaired immunologic activity may be a useful tool for preparation of antiserum for immunochemical determination of human plasma kininogen.

Alkylation↗
PubMed1981

Potentiation of bradykinin with synthetic peptides on guinea pig ileum.

Potentiation of the activity of bradykinin on the isolated guinea pig ileum was studied using a designed test system with the synthetic peptides Leu-Val-Glu-Ser-Ser-Lys, Thr-Pro-Val-Ser-Glu-Lys, derivatives of the former coupled to the N- and C-terminals of bradykinin and two peptides with phenylalanine substituted with its isomer L-3-amino-3-phenylpropanoic acid in the 5- and 5,8-positions in bradykinin respectively. On average, two times potentiation effects were obtained at 10-6 to 10-8 M concentrations of the peptides. After elimination of the basic lysine no potentiation occurred with synthetic Leu-Val-Glu-Ser-Ser. With the [beta Phe5,8]-bradykinin a mixed sensitizing/potentiating effect was observed, suggesting that a separation of the two effects may be difficult with an intact receptor structure of this kind. This peptide was not hydrolyzed by carboxypeptidase B or chymotrypsin.

Animals↗
PubMed1979

Microheterogeneity of human kininogen by isoelectric focusing and crossed immunoelectrophoresis.

LMW kininogen was isolated from whole human plasma by gel filtration on Sephadex G-200 (Kav 0.34) followed by DEAE-chromatography according to earlier established methods. Further purification was performed with specific Sepharose-antibody columns to remove protein contaminants, avoiding procedures which may denature kininogen. The microheterogeneity was investigated by isoelectric focusing in column in the pH-gradients 3.5-10, 4-6 and 3.5-5. Kininogen components were determined by single radial immunodiffusion against monospecific anti-human kininogen serum, in comparison with focusing of whole plasma. 40% of isolated as well as whole plasma kininogen focused at pI 4.5; the respective focusing ranges were pI 4.4-4.7 (60--80%) and pI 4.3-4.6 (92%). The results were verified by crossed immunoelectrophoresis. The pI 4.5 component is apparently the main native form of human kininogen as shown by focusing of whole human blood bank plasma. Earlier described difficulty of separating kininogen and alpha2HS-glycoprotein was verified by crossed immunoelectrophoresis which showed approximately seven kininogen components after focusing in polyacrylamide gel electrophoresis at pI 4.5-5.0 and four alpha 2HS components at pI 4.2-4.6.

Chromatography, Gel↗
PubMed1979

Human kininogen from Cohns Fraction IV: comparisons of antigenicity and multiple forms.

Kininogen was isolated from Cohns fraction IV by DEAE-chromatography, gel filtration and ammonium sulphate precipitation. Immunologically pure kininogen was prepared by removal of protein impurities using specific immunoadsorbents with Sepharose-bound antibody. Anti-kininogen serum was raised in rabbits against the pure antigen. Comparison with anti-kininogen sera prepared with the biologically active LMW antigen from whole plasma suggested antigenic identity by double immunodiffusion analysis. The Cohn-kininogen was shown to contain mainly two components (85%) in about equal amounts focusing with peaks at pI 4.2 (42%) and pI 4.3 (43%). These represent apparently structurally altered forms of the native plasma kininogen focusing at pI 4.5-4.6 (54%), which occurred as a minor component (13%).

Epitopes↗