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Biomedical subjects

U Turpeinen

Publications and source records attributed to U Turpeinen.

61 records · Page 4Linked to original sources
PubMed1985

Liquid chromatography of free hydroxyproline in serum.

We report a "high-performance" liquid-chromatographic method for measuring free hydroxyproline in serum. After separating the free hydroxyproline from the protein- and peptide-bound forms by centrifugal ultrafiltration, we derivatize the free form with 4-dimethylaminoazobenzene-4'-sulfonyl ("dabsyl") chloride and separate and quantify the derivative on a C18 chromatographic column. The mobile phase is sodium acetate buffer and acetonitrile, in a multilinear solvent gradient. The derivative is detected at 436 nm. Mean analytical recovery was 73%. The assay curve is linear from 14 to 213 pmol of hydroxyproline per 5-microL injection. The within- and interassay CVs were 8% at 10.7 mumol/L hydroxyproline and 10% at 13.5 mumol/L hydroxyproline, respectively.

Adult↗
PubMed1983

Studies on the antigenicity and carbohydrates of human low molecular weight kininogen.

Native low mol. wt (LMr) kininogen from human plasma and a kinin-free kininogen from Cohn's plasma fraction IV (HC-antigen) were isolated and studied with regard to their immunological reactivity and carbohydrate heterogeneity. Antisera were prepared against the conformational and sequence-dependent determinants of the heavy chain which is the common denominator of plasma kininogens. The molecules were characterized by single radial immunodiffusion and SDS gel electrophoresis. The effect of exoglycosidase treatment was investigated by a radioimmunoassay. It was found that the antigenic combining sites were not influenced by the partial removal of carbohydrates. These results suggest that the determinant structures of LMr kininogen reside in the peptide backbone of the protein. Carbohydrate heterogeneity was shown by different binding to concanavalin A and wheat germ lectin. With concanavalin A 52% of the immunoreactive HC-antigen was reactive compared to 76% of the native LMr kininogen. The weak reactivity (11%) of the HC-antigen towards the wheat germ lectin indicates that the N-acetylglucosamine residues are apparently blocked or missing. Immunoreactive kininogen was in all cases measured by single radial immunodiffusion or an RIA. The molecular nature of the heterogeneity is discussed in relation to the known isoelectric variations of kininogen.

Antigens↗
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↗
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↗