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On the activation of bovine plasma factor XIII. Amino acid sequence of the peptide released by thrombin and the terminal residues of the subunit polypeptides.

A blood coagulation factor, Factor XIII, was highly purified from bovine fresh plasma by a method similar to those used for human plasma Factor XIII. The isolated Factor XIII consisted of two subunit polypeptides, a and b chains, with molecular weights of 79,000 +/- 2,000 and 75,000 +/- 2,000, respectively. In the conversion of Factor XIII to the active enzyme, Factor XIIIa, by bovine thrombin [EC 3.4.21.5], a peptide was liberated. This peptide, designated tentatively as "activation peptide," was isolated by gel-filtration on a Sephadex G-75 column. It contained a total of 37 amino acid residues with a masked N-terminal residue and C-terminal arginine. The whole amino acid sequence of "Activation peptide" was established by the dansyl-Edman method and standard enzymatic techniques, and the masked N-terminal residue was identified as N-acetylserine by using a rat liver acylamino acid-releasing enzyme. This enzyme specifically cleaved the N-acetylserylglutamyl peptide bond serine and the remaining peptide, which was now reactive to 1-dimethylamino-naphthalene-5-sulfonyl chloride. A comparison of the sequences of human and bovine "Activation peptide" revealed five amino acids replacements, Ser-3 to Thr; Gly-5 to Arg; Ile-14 to Val; Thr-18 to Asn, and Pro-26 to Leu. Another difference was the deletion of Leu-34 in the human peptide. Adsorption chromatography on a hydroxylapatite column in the presence of 0.1% sodium dodecyl sulfate was developed as a preparative procedure for the resolution of the two subunit polypeptides, a or a' chain and b chain, constituting the protein molecule of Factor XIII or Factor XIIIa. End group analyses on the isolated pure chains revealed that the structural change of Factor XIII during activation with thrombin occurs only in the N-terminal portion of the a chain, not in the N-terminal end of the b chain or in the C-terminal ends of the a and b chains. From these results, it was concluded that the activation of bovine plasma Factor XIII by thrombin must be accompanied by a limited proteolysis of the arginyl-glycyl bond located in the N-terminal region of the a chain, liberating the "Activation peptide." The possibility of activating Factor XII with other porteinases was examined using Factor Xa [EC 3.4.21.6], Factor XIIa, kallikreins [EC 3.4.21.8], urokinase [EC 3.4.99.26], trypsin [EC 3.4.21.4], ficin [EC 3.4.22.3], papain [EC 3.4.22.2], and bromelain [EC 3.4.22.4]. Among these enzymes, only bromelain and trypsin showed clear activating effects.

Amino Acid Sequence↗

A serum haemagglutinating property dependent upon polycarboxyl groups.

A serum agglutinin reactive with red cells in the presence of polycarboxyl groups is reported. It is likely that this represents an additional example of the type of agglutinin previously described as agglutinating red cells in the absence of ionized calcium. Experimental evidence is presented indicating that it is free polycarboxyl groups that potentiate agglutination and that any metal ion, such as calcium, capable of chelating with these groups will prove to be inhibitory.

ABO Blood-Group System↗

A further example of the low frequency antigen Pta.

The third Pt(a+) family is described and it has been shown that the red cell antigen is denatured when treated with proteolytic enzymes, but unaffected by neuraminidase and 2-aminoethylisothiouronium bromide treatment.

Blood Group Antigens↗

Use of standardized protease enzymes for antibody screening of blood donor samples with the microplate system AutoAnalyzer.

Papain, bromelin and ficin can be standardized by the casein method for use in red blood cell antibody screening tests. The minimal and optimal enzyme activity for detecting blood group antibodies in donors, using the new Automated Pre-Transfusion Blood Testing System Olympus PK7200 by the two-stage method for all three enzymes, is one casein unit. One casein unit of proteinase activity changed the red blood cell surface charge to a low plateau value as measured by electrophoretic mobility and sialic acid content, and removed sterically inhibiting structures of surface protein as detected by SDS-PAGE.

Autoanalysis↗

Differences in substrate specificities for cysteine proteinases used in blood group serology, and the use of bromelain in a two-phase inhibitor technique.

Because substrate specificities differ between proteolytic enzymes and because knowledge of the optimal enzyme activity levels is necessary in order to standardize procedures used in antibody screening, a study was made of the best common assay method for the routinely employed enzymes bromelain, papain and ficin. Casein degradation was found better suited to this purpose than azoalbumin. With standardization achieved, a useful two-phase bromelain inhibitor technique was devised using bromelain at 20 casein units of activity. This method improved upon the one-stage bromelain technique in terms of sensitivity, freedom from false positive reactions and it compared well with the two-phase papain inhibitor technique.

Albumins↗

Action of glycosyl transferases upon "Bombay" (Oh) erythrocytes. Conversion to cells showing blood-group H and A specificities.

Individuals of the rare "Bombay" (Oh) blood-group phenotype lacking, due to a genetic defect, the alpha(1-2)fucosyl transferase, which is responsible for converting blood-group H precursor substances to H-specific structures. Treatment with GDP-fucose and alpha(1-2)fucosyl transferase prepared from gastric mucosa of O individuals to transform native or ficin-treated "Bombay" erythrocytes into cells phenotypically resembling O cells. The transformation was achieved, however, after prior incubation of the "Bombay" erythrocytes with neuraminidase, indicating that blood-group H precursor molecules on the surface of these cells are masked by sialyl residues. Blood-group A specificity was conferred upon neuraminidase-treated "Bombay" cells by enzymatic transfer of alpha-N-acetylgalactosamine residues, in addition to alpha-fucose residues.

ABO Blood-Group System↗

Persistence of cefotetan on red blood cells.

BACKGROUND: Cefotetan can cause severe immune hemolytic anemia that may persist long after the drug is discontinued. To study the binding of cefotetan to RBCs, patients who received cefotetan were followed and tested for the presence of antibody to cefotetan. STUDY DESIGN AND METHODS: Patients receiving cefotetan were identified from pharmacy and nursing records. Blood samples obtained for routine hematology tests were analyzed. Cefotetan binding to patients' RBCs was tested using a previously characterized high-titer anticefotetan serum by gel technique. To determine the minimum amount of drug necessary for binding to occur, RBCs were incubated with serial dilutions of cefotetan at pH 7.4. RESULTS: Sixty patients receiving 1 to 25 g i.v. (median, 2 g) of cefotetan were followed for 1 to 123 days (median, 18 days). All were initially positive, for cefotetan on RBCs. Positivity persisted for up to 98 days after the last dose of drug. Fifteen patients became negative during follow-up. The first negative sample occurred at Day 30 to 123. Using the midpoint between the last positive and first negative to estimate of the duration of positivity, we estimate that cefotetan remains RBC-bound for 16.5 to 92 days (median, 67.5 days). During the follow-up period, five patients developed anticefotetan detectable in the serum. Twenty patients receiving other cephalosporin antibiotics showed no specific reactivity of their RBCs with anticefotetan. In vitro studies showed a minimum necessary drug concentration of 1 micromol/L at physiologic pH, which was not significantly altered by RBC pretreatment with ficin, sialydase, or DTT. CONCLUSIONS: Cefotetan is tightly bound to RBCs after intravenous administration and remains detectable for weeks after the last dose. Antibodies to cefotetan may occur in about 8 percent of patients receiving the drug. The minimum necessary concentration for RBC binding is low compared to an estimated plasma concentration of 240 micromol/L from a single i.v. dose of 1 g.

Anemia, Hemolytic, Autoimmune↗

Protease-induced constriction in rats' bronchi.

A method is described which allows quantitative measurements of bronchomotor function in vitro in all parts of the tracheobronchial tree. With this method it was observed that chymotrypsin, trypsin and ficin elicted contraction in the intrapulmonary airways of rats. The response could be abolished or diminished by phentolamin and atropine. Physostigmine did not potentiate the response. It is concluded that chymotrypsin operates mainly through alpha-adrenoreceptors, whereas trypsin and ficin operate through both a alpha-adrenoreceptors and cholinoceptive receptors.

Airway Resistance↗

Purification and characterization of extracellular cysteine protease inhibitor, ECPI-2, from Chlorella sp.

An extracellular cysteine protease inhibitor (ECPI-2) was purified to homogeneity from the culture filtrate of Chlorella sp. 4533 by the combination of various column chromatographies. The molecular mass of the inhibitor was estimated to be 340 kDa by SDS-PAGE. The inhibitor was extremely heat-stable under acidic or neutral condition. ECPI-2 exhibited an inhibitory activity against the proteolytic activity of papain, ficin, or chymopapain, but not against stem bromelain or cathepsin B. The inhibitor showed no inhibitory activity against trypsin, alpha-chymotrypsin or thermolysin. ECPI-2 contains 33.6% carbohydrate residues by weight and inhibits papain at a molar ratio of 1:2. The proteolysis of the inhibitor by trypsin or alpha-chymotrypsin was apparent, but the inhibitory activity of ECPI-2 was unaffected by these enzymes. The alpha-chymotrypsin hydrolysis product from ECPI-2 was further separated into six fractions by gel filtration. From these results, it is suggested that ECPI-2 has several reactive sites for papain.

Algal Proteins↗