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Biomedical subjects

M Kloczewiak

Publications and source records attributed to M Kloczewiak.

36 records · Page 2Linked to original sources
PubMed1983

Interaction of fibrinogen with staphylococcal clumping factor and with platelets.

Fibrinogen, a clottable plasma glycoprotein, participates in cell adhesion phenomena involving prokaryotic cells, e.g. staphylococci, and eukaryotic cell fragments, e.g. platelets. Among the three chains (alpha, beta, gamma) of human fibrinogen, the gamma chain bears the main site recognizing the staphylococcal clumping receptor and human platelet receptor induced by ADP. The platelet receptors are also recognized, albeit less avidly, by a site associated with the alpha chain. The gamma chain site recognizing staphylococcal clumping factor exists on the COOH-terminal segment of this chain encompassing the 15 residues (gamma 397-411) including the COOH-terminal valine. The location of the gamma chain site interacting with the human platelet receptor had been pinpointed to the 27 residue CNBr COOH-terminal segment (gamma 385-411). The results of enzymatic degradation of the 27-residue peptide indicate that the continuity of the last 15 amino acid residues at the COOH-terminal end of the gamma chain of human fibrinogen seems to be essential for its interaction with human platelets. The sequence of the gamma chain interacting with the platelet receptor (gamma 385-411) indicates that this segment is a unique region of fibrinogen endowed with three important functions: cross-linking of fibrin, clumping of staphylococci, and aggregation of platelets. [Note added in proof: Recently we obtained evidence that dodecapeptide gamma 393-411 fully retains platelet receptor recognition site (Kloczewiak et al. 1983. Clin. Res 31:534A.)]

Amino Acid Sequence↗
PubMed1983

Recognition site for the platelet receptor is present on the 15-residue carboxy-terminal fragment of the gamma chain of human fibrinogen and is not involved in the fibrin polymerization reaction.

A pentadecapeptide, derived from a staphylococcal protease digest of the 27-residue carboxy-terminal cyanogen bromide fragment of human fibrinogen gamma chain, inhibits binding of 125I-fibrinogen to human platelet receptors and aggregation of platelets induced by ADP and fibrinogen. Amino acid composition and NH2 terminal analysis indicate that the isolated pentadecapeptide corresponds to residues 397 to 411 of the gamma chain. A synthetic peptide also inhibited binding of 125I-fibrinogen and aggregation of platelets. In contrast, the isolated pentadecapeptide and its parent 27-residue fragment lack inhibitory activity toward the polymerization reaction of fibrin monomer. Thus, the site recognizing the platelet receptor encompasses residues 397-411 of the gamma chain of fibrinogen and is distinct from the site(s) involved in polymerization of fibrin monomers.

Amino Acid Sequence↗
PubMed1982

gamma and alpha chains of human fibrinogen possess sites reactive with human platelet receptors.

Fibrinogen, a clottable plasma protein, agglutinates both prokaryotic cells (e.g., staphylococci) and eukaryotic cell fragments (e.g., platelets) through interaction with specific receptors. To identify the region of the fibrinogen molecule responsible for its interaction with human platelets, we prepared polypeptide chain subunits (alpha, beta, and gamma) of human fibrinogen by reduction and carboxymethylation. A mixture of the chains induced aggregation (clumping) of human platelets separated from plasma proteins and treated with ADP. When individual chains of fibrinogen were tested, gamma-chain multimers caused platelet aggregation at a molar concentration comparable with that of intact human fibrinogen. The beta chain remained inactive, and the alpha chain was 1/4th to 1/5th as reactive as the gamma chain. Monospecific antibody fragments against the gamma chain inhibited binding of 125I-labeled fibrinogen to the human platelet receptor and blocked aggregation of platelets induced by ADP in the presence of fibrinogen or gamma-chain multimers. These results indicate that the gamma chain of human fibrinogen bears the main site for interaction with the platelet receptor.

Antigen-Antibody Reactions↗
PubMed1981

Role of kidney in the catabolic clearance of human platelet antiheparin proteins from rat circulation.

UNLABELLED: Stimulated platelets release at least two antiheparin proteins: platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4) from which beta-thromboglobulin (beta TG) is derived. We have found previously marked elevation of LA-PF4/beta TG antigen in platelet poor plasma of patients with chronic renal failure, whereas levels of PF4 remained normal. Therefore, we examined the role of the kidneys in the metabolic clearance of LA-PF4/beta TG and PF4. The supernates of aggregates of thrombin-stimulated human platelets were injected into sham operated control rats, nephrectomized rats, and into rats with acute ureteral ligation. The disappearance of human LA-PF4/beta TG antigen and PF4 in rat plasma determined by specific radioimmunoassays followed biphasic exponential curves. The half-lives (t1/2) for the fast and slow components of LA-PF4 in control rats were 6.4 and 68.4 min. Nephrectomy significantly increased these times to 9.7 and 144 min, while ureteral ligation resulted in no significant change. Comparison of the level of LA-PF4/beta TG antigen and of creatinine in aorta and in renal vein showed 25%-30% extraction of these compounds by the kidney. Less than 0.1% of the total LA-PF4 antigen injected was recovered in the urine of control rats. In contrast to these results, the clearance of PF4 was not affected by nephrectomy. IN CONCLUSION: (1) functional renal tissue is necessary for normal clearance of LA-PF4/beta TG, but renal excretion does not play a major role in its elimination suggesting that the protein is catabolized by the kidney; and (2) catabolic clearance of PF4 does not depend on functioning kidney tissue.

Animals↗
PubMed1976

Studies on chemically modified fibrinogen.

Treatment of fibrinogen with maleic acid anhydride renders fibrinogen unclottable depending on the degree of modification of the molecule. According to radioactive studies the release of fibrinopeptides by thrombin or reptilase is undisturbed. The incoagulability is due to inhibition of the polymerization process of fibrinmonomers derived from modified fibronogen, mainly caused by the increase of electronegative charges upon the fibrogen molecule. According to discelectrophoretic analysis modified fibrinogen fails to produce fragments D and E following plasmic digestion, however, may be degraded to high molecular weight products. Modified fibrinogen reveals some similarities to abnormal fibrinogens in congenital dysfibrinogenemia with regard to its functional properties.

Anhydrides↗
PubMed1976

Molecular size and amino acid composition of H-2d antigen solubilized in Nonidet P-40.

H-2d antigenic material solubilized by the detergent Nonidet P-40 from L-1210 mouse leukemia cells was isolated by gel filtration on Bio-Gel P-100. A single peak eluted in the void volume consisted of about 90% protein, 8% hexose and traces of sialic acids. In sedimentation velocity runs, the antigen sedimented as a single peak of 3-1 S. Molecular weight determined by sedimentation equilibrium as well as calculated from amino acid composition was found to be in the range of 53,000 daltons and approx. 45,000-51,000 when calculated from sodium dodecyl sulfate polyacrylamide gel electrophoresis. Secondary structure of H-2d glycoprotein was predicted from the amino acid composition. For NP-40-solubilized H-2d antigen, about 34% of helix, 13% beta sheet and 41% turns was found.

Amino Acids↗
PubMed1975

Bovine fibrinogen modified with 3H-acetic anhydride (3H-AcOAc).

The method is described for acetylation of bovine fibrinogen with 3H acetic anhydride (3H-AcOAc). Preparations acetylated at pH 7.8 with 10 to 40 molar excess of 3H-AcOAc were found to contain 8 to 13 moles of acetyl residues per mole of fibrinogen. The content of clottable protein and ultraviolet (UV) spectra were unchanged as compared with control unlabeled preparations. The rate of clotting with thrombin was only slightly affected. The investigations on distribution of 3H-acetyl groups in products of proteolysis of acetylated fibrinogen by thrombin demonstrated a preferential acetylation of fibrinopetide A and absence of radioactive tracer in fibrinopeptide B. Incorporation of the label into fibrinopeptide A opens the possibility for application of fibrinogen labeled with 3H-AcOAc as a convenient substrate for selective investigation on the enzymatic phase of clotting.

Acetylation↗