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Biomedical subjects

M Steinbuch

Publications and source records attributed to M Steinbuch.

At least 55 records · Page 3Linked to original sources
PubMed1983

The alpha 2 macroglobulin/thrombin interaction in the presence of hydroxylamine.

The influence of a primary amine, hydroxylamine, on the interaction between alpha 2 macroglobulin (alpha 2M) and thrombin was analyzed by electrophoretic and enzymatic methods. Hydroxylamine (final concentrations 0.01 M and 0.1 M) was added to the alpha 2M solution 3 to 5 min before thrombin. In these conditions hydroxylamine had no direct influence on alpha 2M itself. The inhibition of thrombin activity by alpha 2M was still possible and alpha 2M/thrombin complexes were observed. However the rate of inhibition of the clotting activity of thrombin was diminished in function of the hydroxylamine concentration. The complexes obtained in the absence of the nucleophylic agent were resistant to SDS dissociation, whereas those obtained in the presence of hydroxylamine were dissociated by SDS. In both cases, the amount of alpha 2M polypeptide chains cleaved by thrombin was the same (50%). In conclusion, hydroxylamine does not prevent the formation of alpha 2M/thrombin complexes, but it reduces the covalent binding of the enzyme to the inhibitor in a concentration dependent fashion, leading to the formation of "abnormal" complexes.

Electrophoresis, Polyacrylamide Gel↗
PubMed1983

Structural arrangement in the alpha 2-macroglobulin--thrombin complex.

The cysteine sulfhydryl groups of alpha 2-macroglobulin (alpha 2M) generated upon thrombin complex formation are in contact with the proteinase surface as evidenced by singlet--singlet energy transfer measurements from N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulfonic acid-labeled thiol functions of alpha 2M to fluorescein isothiocyanate-labeled thrombin. The thrombin-alpha 2M binding is normally covalent, but the presence of hydroxylamine during the reaction leads to the formation of a non-covalent complex. The transfer energy determinations show that the alpha 2M binding sites of thrombin are quite similar, whatever covalent or non-covalent binding occurs.

Chymotrypsin↗
PubMed1983

A simplified technique for the isolation of the fourth complement component.

Prothrombin complex (P.C.) preparations obtained by batch adsorption onto DEAE-Sephadex are highly enriched in C4. Based on this observation a technique has been elaborated where the P.C. analogue is further submitted to precipitation by ethanol and batch adsorption of impurities on DEAE-Cellulose. Unaltered C4 is obtained in a 2 days process with a yield corresponding to 40% of the starting material (cryoconcentrate supernatant).

Blood Coagulation Factors↗
PubMed1983

Some proteins not belonging to the clotting or to the kallikrein-kinin system altered by kallikrein.

Plasma kallikrein activation occurs frequently during blood drawing and subsequent plasma handling. The purified enzyme was incubated with ceruloplasmin, inter-alpha-trypsin inhibitor and complement factor C4. Proteolysis caused by this enzyme was compared with the degradative effects of plasmin and thrombin. Among these proteins C4 proved to be most easily degraded; its cleavage products can interact with C4-binding protein.

Blood Coagulation↗
PubMed1982

Heparin and the progressive anti-thrombin activity of alpha 2-macroglobulin.

Interactions between alpha 2-macroglobulin (alpha 2M) and thrombin have been studied by spectroscopic, isotopic and electrophoretic methods in presence or in absence of heparin. It is shown that thrombin binds to alpha 2M in a 1:1 ratio. Fluorescamin labelled heparin of Mr 7 000 interacts with thrombin to form a 2:1 molar complex. This complex does not bind to alpha 2M and is unable to achieve any proteolytic cleavage of this protein. In contrast the interaction of alpha 2M with chymotrypsin is not significantly affected by the mucopolysaccharide. Moreover, heparin is unable to react with alpha 2M bound thrombin.

Antithrombins↗
PubMed1981

Spectroscopic and photoreduction studies of copper chromophores in ceruloplasmin.

Photoreduction of native ceruloplasmin, using the 454.5-nm line of an Ar+ laser, enables the identification of type-Ia, type-Ib and type-II copper. The circular dichroic spectra of N--3-bound type-II copper and SCN-- -bound type-II copper are obtained by the same procedure after anionic treatment of ceruloplasmin. From circular dichroic and resonance Raman evidence it appears that some of type-Ia and type-Ib copper ligands differ. Type-Ib copper ligands seem to the same as type-I copper in plastocyanin and azurin. Even though type-Ib copper is coordinated to one sulfur of cysteine and one sulfur of methionine (or disulfide of cystine), the methionine sulfur is not a ligand for type-Ia copper.

Azides↗
PubMed1980

A new subfraction of routine fractionation.

The prothombin complex is adsorbed from plasma or cryoconcentrate supernatant onto DEAE-sephadex A50. The adsorbent is washed several times with 0.21 M NaCl. The first washing proved to be a new subfraction of routine fractionation suitable as starting material for the purification of several proteins such as C1-inactivator, N-carboxypeptidase, ceruloplasmin and kallikrein.

Adsorption↗
PubMed1979

[Purification and concentration of albumin solutions by diafiltration using a parallel membrane dialyzer].

The last two years, artificial Kidneys have been used for purification and concentration of human serum albumin solutions coming from plasma cracking in two Blood Transfusion Centers. Results are easily reproducible and the apparatus is reliable and of low cost. The properties of dialysis and ultrafiltration of the A.N. 69 membrane are useful for eliminating ethanol and water. The artificial Kidneys are effective at low pressure. It is then possible to use peristaltic pumps and to have a closed circuit. The whole apparatus must be sterilized with chemical reagents.

Dialysis↗
PubMed1979

Isolation of human C1q as a by-product of routine fractionation.

Clq can be isolated as a by-product of large scale fractionation. The euglobulins of fraction III are submitted to chromatography on CM-cellulose in a batch-procedure. The active fraction being frequently contaminated by lysozyme the protein can be further purified by gel-filtration in the presence of carbohydrates. The purified Clq is suitable for the detection of immune complexes.

Chemical Fractionation↗
PubMed1979

Side products of routine plasma fractionation. I. Serum cholinesterase (EC 3.1.1.8).

Cholinesterase (EC 3.1.1.8) for intravenous use has been obtained from fraction IV, a by-product of ehtanol fractionation. A four-step procedure has been developed associating precipitation by Rivanol and PEG 4000 with chromatography on DEAE-cellulose. The yield corresponds to 30--35% of the activity found in fraction IV. Vials containing 5000 U of CHE stabilized by 2.5% albumin have been prepared. The pyrogen-free product is well tolerated in the human.

Centrifugation↗