Purification and properties of bovine prothrombin

Unique properties of prothrombin in the bullhead shark Heterodontus japonicus: the first report of purification and characterization of a blood coagulation factor in Chondrichthyes

Prothrombin is a serine protease precursor of the blood coagulation system. In this study, the primary structure of prothrombin of a cartilaginous fish, bullhead shark (Heterodontus japonicus), was determined using RNA-Seq and the protein was purified from the blood plasma. Bullhead shark prothrombin was found to be comprised of four domains, as in the case of reported mammalian homologues. Two arginine residues that should be cleaved by activated factor X were found in the amino acid sequence of the shark prothrombin, but only one of the two cleavage sites for thrombin or meizothrombin was conserved. The apparent molecular mass of the shark prothrombin on SDS-PAGE was 110 kDa, whereas that of its amino acid sequence was 65 kDa. Potential N-glycosylation sites were found at 79th, 108th, 121st, 179th, 199th, 507th, and 527th asparagine residues in the shark prothrombin, and treatment with N-glycosidase reduced the molecular mass to 65 kDa. This indicates that, in contrast to human prothrombin, which has only 7-kDa N-glycans, the prothrombin of the shark is highly N-glycosylated. This study is the first to report on the purification and characterization of blood coagulation factors in a cartilaginous fish.

Taking the Thrombin “Fork”

The proverb that probably best exemplifies my career in research is attributable to Yogi Berra (http://www.yogiberra.com/), ie, “when you come to a fork in the road … take it.” My career is a consequence of chance interactions with great mentors and talented students and the opportunities provided by a succession of ground-breaking improvements in technology.

Acid-induced denaturation and refolding of prothrombin

Structural transitions of the blood coagulation factor prothrombin (extracted from goat blood) in response to reduction of pH were investigated by fluorescence, circular dichroism and light scattering measurements. The study revealed the presence of a partially unfolded state at around pH 3.5, characterized by marked enhancement of fluorescence from ANS bound to the protein, increase of bimolecular rate constant for tryptophan fluorescence quenching and a sharp peak in the light scattering intensity. Further lowering of the pH caused reversal of the trend of variation of these parameters, suggesting that prothrombin folds back to a compact state containing native-like secondary structural elements. The refolded state at low pH (<pH 3) fits the description of the A-state, the end-point of acid-induced denaturation process of several other monomeric proteins, and is a possible candidate for the class of folding intermediates known as molten globules.

Thrombin generation and presence of thrombin receptor in ovarian follicles

Prothrombin, once converted to its enzymatically active form (i.e., thrombin), induces a broad spectrum of cellular responses in both vascular and avascular tissues. Bovine ovarian granulosa cells isolated from healthy follicles of various sizes contain both prothrombin mRNA and immunologically reactive prothrombin that appears to be identical to prothrombin in follicular fluid and plasma. When tissue factor, the primary physiological activator of thrombin generation in plasma, is used to initiate thrombin formation, the profile of prothrombin-to-thrombin conversion is similar in follicular fluid and plasma. The conclusion that biologically functional prothrombin is synthesized by granulosa cells is further supported by evidence that mRNA for gamma-glutamyl carboxylase, an enzyme essential for the vitamin K-dependent posttranslational modification of prothrombin, is expressed in granulosa cells in a manner similar to prothrombin mRNA. Thrombin's biological effects are mediated through selective proteolytic cleavage and activation of specific receptors. Bovine granulosa cells possess thrombin receptor (PAR-1) mRNA, and as seen with prothrombin mRNA and gamma-glutamyl carboxylase mRNA, cells isolated from small follicles possess more PAR-1 mRNA than cells from large follicles. Thrombin receptor expression by cells in close proximity to an active thrombin-generating system suggests that these factors may be important mediators of cellular function in the ovarian follicle.

A novel one-step purification of human alpha-thrombin after direct activation of crude prothrombin enriched from plasma

Crude prothrombin enriched from human plasma was directly activated to generate alpha-thrombin without prior exhaustive purification of the proenzyme using a combination of several different types of chromatographic techniques, as in all previously described methodologies. Activated thrombin was separated from other components in a single step by taking advantage of its highly specific affinity to heparin immobilized on a matrix support of Sepharose CL-6B. On the basis of the data presented herein, we have demonstrated the ease with which at least 25 mg of a highly purified enzyme (greater than 97% homogeneous by laser densitometry) can be obtained per litre of plasma. Our product exhibits a specific activity of at least 4000 National Institutes of Health units/mg and is stable after being freeze-dried for the purpose of long-term storage.

Vitamin K-dependent carboxylase: partial purification of the enzyme by antibody affinity techniques

The vitamin K-dependent carboxylase activity of bovine liver microsomes has been purified 500-fold by adsorption to an antiprothrombin column and elution with a dodeca peptide which competes with a prothrombin precursor enzyme recognition site. The purified enzyme is devoid of bound precursors, and has the same ratio of vitamin K epoxidase activity to carboxylase activity as the crude microsomal preparation.

Rapid purification of factor IX, factor X and prothrombin by immunoaffinity and ion exchange chromatography

This study describes a rapid purification of factor IX, factor X and prothrombin by immunoaffinity and ion exchange chromatography. Human factor IX was purified from plasma in 34% yield using barium sulfate adsorption and immunoaffinity purification. The specific clotting activity of purified factor IX was 269 units/mg, with an apparent molecular weight of 57,000 in the presence of sodium dodecyl sulfate on polyacrylamide gels. The immunodepleted, factor-IX deficient plasma was chromatographed on a dextran sulfate agarose column which resolved prothrombin and factor X in highly purified states and with approximately 50% yield. The specific activities of prothrombin and factor X obtained by this procedure were 24 units/mg and 147 units/mg respectively. Both proteins isolated by this method showed a single component on SDS gel electrophoresis and the molecular weights of intact prothrombin and factor X were 72,000 and 67,000 respectively.

Calcium-dependent changes in properties of human prothrombin: a study using high-performance size-exclusion chromatography and gel-permeation chromatography

High-performance size-exclusion chromatography using a TSK 3000 SW column and aqueous gel filtration with Sephacryl S-200 SF have been used to characterize the effects of calcium ions on the hydrodynamic properties of human prothrombin and prethrombin 1. The results suggest that the effective hydrodynamic radius of prothrombin is less in the presence than in the absence of calcium ions. In addition, when using the TSK-3000 SW column, Ca2+-dependent formation of a hydrophobic site in the fragment 1 region of prothrombin results in an apparent further decrease in hydrodynamic radius.

Isolation and characterization of a proteolytic enzyme from the venom of the snake Bothrops jararaca (Jararaca)

Bothropasin, one of the proteases from the venom of Bothrops jararaca active on casein, was isolated by ammonium sulfate precipitation, DEAE-cellulose and DEAE-Sephadex A-50 chromatographies and Sephadex G-100 column filtration. The preparation possessed no other detectable activities which are present in the crude venom. Addition of Ca2+ during purification stabilized the enzyme. The endopeptidase was inhibited by EDTA and EGTA; Ca2+ did not restore the activity of the inhibited enzyme. The material was homogeneous by polyacrylamide gel electrophoreses at different pH values, immunoprecipitation and crossed immunoelectrophoresis. By SDS-polyacrylamide gel electrophoresis the denatured and reduced enzyme had only a 48,000 molecular weight band. In the presence of 6 M guanidine-HCl and 0.1 M beta-mercaptoethanol the preparation showed a value of 49,870 by sedimentation equilibrium. The native tertiary structure of the protein is dependent on S-S and metal bonds. The denatured and reduced enzyme, in the presence of EDTA, showed a molecular weight of 37,300 by sedimentation equilibrium, a value which was also confirmed in SDS-polyacrylamide gel electrophoresis. The enzyme hydrolyzed five peptide bonds: His-Leu (5-6), His-Leu(10-11), Ala-Leu(14-15), Tyr-Leu(16-17) and Phe-Phe(24-25) in the B-chain of oxidized insulin.

Prothrombin--membrane interaction. Effects of ionic strength, pH, and temperature

The effects of ionic strength, pH, and temperature on three separate aspects of prothrombin-phospholipid membrane binding were studied. The three parameters include a calcium-dependent protein transition, a calcium-membrane interation, and, finally, the binding of calcium-saturated protein to a calcium-saturated phospholipid membrane. The results are consistent with calcium binding to carbonyl groups in the protein and to phosphate in the phospholipids. These interactions show the expected pH profiles and sensitivity to ionic strength. Temperature effects indicate a small negative enthalpy change for each process. The binding of calcium-saturated protein to calcium-saturated membrane shows very little variation between pH 6 and pH 9, is accompanied by no detected enthalpy change, and is relatively insensitive to ionic strength. These latter results indicate that ionic calcium bridging between the protein and membrane is not important. A chelation model for prothrombin-membrane binding is proposed where the two interacting species have no net charge; ligands on the protein complete the coordination sphere of membrane-bound calcium and vice versa.

Zymogens and cofactors of blood coagulation

Blood coagulation is a system in which a series of zymogens of serine proteases are sequentially activated. In this regard, there is little fundamental difference between coagulation and the activation of the homologous pancreatic zymogens. There are, however, several aspects unique to coagulation which are discussed in detail. These are (1) the requirement for a high-molecular-weight protein or lipoprotein cofactor for optimal reaction rates, (2) the requirement for membranes or a membrane-like surface which further distinguishes this system; (3) a metal ion requirement for most reactions (in contrast to the pancreatic serine proteases) relating to the content of the newly described amino acid gamma-carboxyglutamic acid in the four vitamin K-dependent proteins, regarding which recent data relating to the metal binding sites on prothrombin are discussed in detail; and (4) the uniqueness of the initiating reactions in comparison to those which activate the pancreatic zymogens, insofar as no enzyme corresponding to enterokinase has been identified. The implications of this phenomenon are analyzed with particular attention to the potential role of the endogenous activity of certain zymogens in initiating coagulation. The article deals finally with the specific problems attendant on analyzing a system in which many serine proteases lacking absolute specificity are generated and regulated.

Pig prothrombin: purification and properties

A procedure for the preparation of highly purified pig prothrombin is described. Compared to the initial clotting activity of the starting plasma, this protein was purified 776 times with a final yield of 8 per cent. The purified zymogen showed a specific activity of 1,460 NH units/mg of protein , a molecular weight of 65,000 as determined by SDS-polyacrylamide disc gel electroesis, E 1.0 mg/ml 1.0 cm, 280 nm = 1.45 at pH 7.0 and the following amino acid composition: Asx 51, Thr 38, Glx 62, Pro 23, Gly44, Ala 25, Half-Cys 30, Val 35, Met 3, Ile 30, Leu 32, Tyr 19, Phe 22, Lys 36, His 8, Arg 28, and Trp 13, which accounts for a minimum molecular weight of 59,370 (carbohydrates not computed). Alanine was found as the only N-terminal residue. Carboxypeptidases A and B failed to release any C-terminal residue. By hydrazinolysis however 0.4 mole of serine was released per mole of prothrombin. The activation of crude and chromatographed pig prothrombin was investigated.

Improved procedures for the purification of selected vitamin K-dependent proteins

Improved methods are described to obtain bovine prothrombin, Factor IX, Protein C, and autoprothrombin III (Factor X, Auto-III) in purified form. The prothrombin had a specific activity of 4,340 Iowa units/mg. Theoretically, a preparation of clean thrombin should have a specific activity of 8,200 U/mg, because 47.08% of the protein in prothrombin is lost when thrombin forms. Such thrombin preparations have been obtained (Arch. Biochem. Biophys. 121, 372 (1967)). The prothrombin concentration of bovine plasma is near 60 mg/liter. Protein C, first isolated by Stenflo (J. Biol. Chem. 251, 355 (1976)), was found to be the precursor of autoprothrombin II-A (Auto-II-A), discovered earlier (Thromb. Diath. Haemorrh. 5, 218 (1960)). Protein C (Factor XIV) was converted to Auto-II-A (Factor XIVa) by thrombin. Digesting purified Auto-III with purified thrombin removed a small glycopeptide from the COOH-terminal end of the heavy chain to yield Auto-IIIm. Auto-III thrombin leads to Auto-IIIm + peptide. Auto-IIIm was not converted to the active enzyme with thromboplastin, and furthermore, inhibited the activation of purified native Auto-III with thromboplastin. Auto-IIIm was also not converted to the active enzymes when the procoagulants consisted of purified Factor VIII, purified Factor IXa, platelet factor 3 and calcium ions. The "activation peptide" released by RVV-X from the NH2-terminal end of the heavy chain and the active enzyme (Auto-Cm) were purified. Auto-III was also activated with purified RVV-X. The same "actid of Auto-Cm. Purified Factor IX developed anticoagulant activity when reacted with an optimum concentration of purified thrombin. A suitable reagent for the assay of Factor IX was prepared by removing prothrombin complex from anticoagulated bovine plasma and restoring the prothrombin and Auto-III concentration with use of the respective purified proenzymes.

A method for the simultaneous isolation of factor X and prothrombin from bovine plasma

1. A method is described for the simultaneous isolation of both Factor X and prothrombin from bovine plasma. The proteins are adsorbed on and eluted from barium sulphate and chromatographed on DEAE-Sephadex and are finally purified by rechromatography on DEAE-Sephadex. 2. The proteins can be purified in 48h from the collection of the blood and the method can be used to process large volumes of plasma. 3. The prothrombin has a molecular weight of 70300; the Factor X, on the other hand, is polydisperse, with most of the protein (86%) having a molecular weight of 56000.