Contribution of fibrin stabilization to clot strength. Supplementation of factor XIII-deficient plasma with the purified zymogen

Deficiency of coagulation factor XIII A subunit caused by the dinucleotide deletion at the 5' end of exon III

A congenital deficiency of the coagulation Factor XIII A subunit (F XIII A) is a rare autosomal recessive disorder that is characterized by a life-long bleeding tendency complicated by a difficulty in healing. Thus far, no molecular genetic analysis of this disorder has been reported. In this study, we demonstrate the molecular abnormalities in a family with this disorder. We performed Northern blot analysis of peripheral blood monocytes obtained from the propositus and found a 4-kb single band of F XIII A mRNA whose size was identical with that of normal subjects. Exons II-XV, which encode all the amino acids, were individually amplified by a polymerase chain reaction (PCR). All PCR products from the propositus had lengths indistinguishable from those of the wild type on agarose gel, suggesting that this defect results from either a point mutation or a short deletion/insertion. The sequencing of F XIII A cDNA from the propositus revealed a deletion of the dinucleotide AG within the AGAG repeat at the position of 210 to 213. Concerning the genomic sequence, a deletion of dinucleotide AG was also demonstrated in the intron B-exon III boundary. This deletion appeared to cause a frameshift mutation making a new stop codon shortly thereafter, and leading to a deficiency of plasma F XIII A. The heterozygosity of the F XIII A deficiency in the patient's offspring was documented by the nucleotide sequences of their exon III.

A microtiter plate transglutaminase assay utilizing 5-(biotinamido)pentylamine as substrate

Transglutaminases belong to an important family of enzymes involved in hemostasis, skin formation, and wound healing. We describe a technique for the measurement of transglutaminase activity using polystyrene microtiter plates coated with N,N'-dimethylcasein. The substrate 5-(biotinamido)pentylamine is covalently incorporated into N,N'-dimethylcasein by transglutaminase in a calcium-dependent reaction. The biotinylated product is detected by streptavidin-alkaline phosphatase and quantitated by measuring the absorbance at 405 nm following the addition of p-nitrophenyl phosphate. The assay is sensitive, specific, and linear at plasma factor XIIIa concentrations between 0.08 and 1.25 micrograms/ml and at purified guinea pig liver transglutaminase concentrations between 0.05 and 0.8 microgram/ml. The intra-assay coefficient of variation is less than 8%. The solid-phase assay was used to quantitate the transglutaminase activity in Escherichia coli extracts expressing recombinant factor XIII A-chains and to analyze factor XIIIa inhibitors. This method will facilitate the analysis of structure-function relationships of the transglutaminases using recombinant DNA methods. Furthermore, screening of natural and synthetic factor XIIIa inhibitors will be expedited by this solid-phase microtiter plate assay.

Quantitation of plasma factor XIIIa activity using fibrin-coated microscopic latex beads

Following exposure to thrombin, monodisperse microscopic polystyrene-divinylbenzene beads coated with a mixed film of lecithin and fibrinogen aggregate as a consequence of interbead fibrin polymerization. These bead aggregates rapidly dissociate in 5 M urea. Treatment of aggregates with factor XIIIa results in a dose-dependent decrease of the rate of aggregate dissociation in urea. The rate of disaggregation is readily quantitated by turbidimetry. We have exploited this phenomenon to develop a rapid and sensitive method for quantitating factor XIIIa activity in plasma. Using 20 microliter of human plasma the method measures the activity of factor XIIIa to a level of 0.03 U ml-1 with a precision of +/-5%.

A turbidimetric method for measuring fibrin formation and fibrinolysis at solid-liquid interfaces

We have developed a rapid and sensitive method by which to quantitate proteolysis of fibrin(ogen) at interfaces. Microscopic polystyrene-divinylbenzene beads coated with a mixed monomolecular film of lecithin and fibrinogen aggregate in aqueous media following exposure to thrombin or enzymes of thrombin-like activity. This aggregation is a consequence of interbead association of fibrin. As an indirect measure of the rate of fibrin formation, the rate of aggregation of beads can be used advantageously to assay enzymes and enzyme regulators pertinent to coagulation. Since the apparent absorbance of monodisperse beads is greater than that of bead aggregates, determination of the rate of change of apparent absorbance of a stirred dispersion of beads following addition of enzyme or enzyme-regulator mixture is a convenient and simple means by which to quantitate the rate of bead aggregation. Using a simple spectrophotometer or aggregometer, the method can be used to quantitate as little as 0.0005 NIH unit of thrombin. Aggregates of fibrin-coated beads can be disaggregated by several proteinases, most notably plasmin. Thus, just as bead aggregation can be used to quantitate effectors of fibrin formation, dissociation of aggregates of fibrin-coated beads can be used to quantitate effectors of fibrinolysis. Using disaggregation as a measure of fibrinolysis, the method is sensitive to as little as 0.005 unit of plasmin. Fibrin(ogen)-coated beads should prove a useful tool for studying proteolysis of fibrin(ogen) in general, and adsorbed fibrin(ogen) in particular.

Haplotypes of the coagulation factor XIII A subunit locus in normal and deficient subjects

Several RFLPs have been detected using a cDNA fragment encoding the amino-terminal half of the A subunit of factor XIII. The RFLPs show little linkage disequilibrium and form many different haplotypes that can be used to identify chromosomes transmitting factor XIII A subunit deficiency. Southern blot analysis of three deficient individuals from two families showed that, in these cases, factor XIII A subunit deficiency did not result from a major gene deletion or rearrangement. Factor XIII A subunit deficiency was found to be associated with three different haplotypes, suggesting heterogeneity in the mutations causing this disorder.

Autoimmune antibody (IgG Kansas) against the fibrin stabilizing factor (factor XIII) system

Serum from a patient who died from massive hemorrhage within 4 months after onset of an acquired bleeding disorder at age 85 contained a potent inhibitor of fibrin stabilization. Other parameters of coagulation and fibrinolysis and his bleeding time were within normal limits. The inhibitor was shown to be an IgG with kappa light chains (IgG Kansas); its specific target was the factor XIII system itself. Although IgG Kansas combined with the virgin [ab] form of the zymogen, it did not block the thrombin-catalyzed conversion to [a'b]. However, IgG Kansas prevented the subsequent Ca2+-mediated activation of [a'b] to a + b, where a denotes the catalytically competent factor XIIIa species. IgG Kansas, in contrast to a previously studied autoimmune antibody from a similar bleeding disorder (IgG Warsaw), could also inhibit the transamidating activity of the preactivated a enzyme.

Primary structure of human coagulation factor XIII

The complete primary structures of the a and b subunits of human factor XIII were determined by a combination of cDNA cloning and amino acid sequencing. The a subunit is composed of 731 amino acids including an activation peptide (37 amino acids), an active site (-Tyr-Gly-Gln-Cys-Glu-), a putative calcium binding site(s), and a thrombin-inactivation site. The functional regions of the a subunit appear to be located in separate exons of its gene. The b subunit consists of 641 amino acids including ten tandem repeats that are homologous with those in at least 13 other proteins. Each GP-I structure in the b subunit is probably encoded by a separate exon.

Amino acid sequence of the a subunit of human factor XIII

Factor XIII is a plasma protein that plays an important role in the final stages of blood coagulation and fibrinolysis. The complete amino acid sequence of the a subunit of human factor XIII was determined by a combination of cDNA cloning and amino acid sequence analysis. A lambda gtll cDNA library prepared from human placenta mRNA was screened with an affinity-purified antibody against the a subunit of human factor XIII and then with a synthetic oligonucleotide probe that coded for a portion of the amino acid sequence present in the activation peptide of the a subunit. Six positive clones were identified and shown to code for the a subunit of factor XIII by DNA sequence analysis. A total of 3831 base pairs was determined by sequencing six overlapping cDNA clones. This DNA sequence contains a 5' noncoding region or a region coding for a portion of a pro-piece or leader sequence, the mature protein (731 amino acids), a stop codon (TGA), a 3' noncoding region (1535 nucleotides), and a poly(A) tail (10 nucleotides). When the a subunit of human factor XIII was digested with cyanogen bromide, 11 peptides were isolated by gel filtration and reverse-phase HPLC. Amino acid sequence analyses of these peptides were performed with an automated sequenator, and 363 amino acid residues were identified. These amino acid sequences were in complete agreement with those predicted from the cDNA. The a subunit of factor XIII contained the active site sequence of Tyr-Gly-Gln-Cys-Trp, which is identical with that of tissue transglutaminase.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acid sequence of the b subunit of human factor XIII, a protein composed of ten repetitive segments

Factor XIII is a plasma protein that participates in the final stages of blood coagulation. The complete amino acid sequence of the b subunit of human factor XIII was determined by a combination of cDNA cloning and amino acid sequence analysis. A lambda gt11 cDNA library prepared from human liver mRNA was screened with an affinity-purified antibody against the b subunit of human factor XIII. Nine positive clones were isolated from 2 X 10(6) phage and plaque-purified. The largest cDNA insert was sequenced and shown to contain 2180 base pairs coding for a portion of the leader sequence (19 amino acids), the mature protein (641 amino acids), a stop codon (TGA), a 3' noncoding region (187 nucleotides), and a poly(A) tail. When the b subunit of human factor XIII was digested with cyanogen bromide, nine peptides were isolated by gel filtration and reverse-phase high-performance liquid chromatography. Amino acid sequence analyses of these peptides were performed with an automated sequenator, and 299 amino acid residues were identified. These amino acid sequences were in complete agreement with the amino acid sequence predicted from the cDNA. The b subunit of factor XIII contained 10 repetitive homologous segments, each composed of about 60 amino acids and 4 half-cystine residues. Each of these repeated segments is a member of a family of repeats present in human beta 2-glycoprotein I, complement factor B, and haptoglobin alpha 1 chain. Three potential Asn-linked carbohydrate attachment sites were also identified in the b subunit of factor XIII.

Fibrinogen and fibrin: biochemistry and pathophysiology

Fibrinogen is a thrombin-coagulable glycoprotein occurring in the blood of vertebrates. The primary structure of the alpha, beta, and gamma polypeptide chains of human fibrinogen is known from amino acid and nucleic acid sequencing. The intact molecule has a trinodular, dimeric structure and is functionally bivalent. Thrombin cleaves short peptides from the amino termini of the alpha and beta chains exposing polymerization sites that are responsible for the formation of fibrin fibers and appearance of a clot. The major physiological function of fibrinogen is the formation of fibrin that binds together platelets and some plasma proteins in a hemostatic plug. In pathological situations, the network entraps large numbers of erythrocytes and leukocytes forming a thrombus that may occlude a blood vessel. Fibrinogen and fibrin are multifunctional proteins. Fibrinogen is indispensable for platelet aggregation; it also binds to several plasma proteins, however, the biological function of this interaction is not completely understood. Fibrin is an essential matrix for regulation of fibrinolysis and for facilitation of cell attachment in wound healing.

Transglutaminases

This paper is intended as a background to the topic of transglutaminases, while focusing on current ideas regarding the biological roles of these enzymes. Specifically, the following topics are discussed: geometry of forming gamma-glutamyl-epsilon-lysine cross-linked structures; energetic considerations; the gamma-glutamyl-epsilon-lysine cross-link; amine incorporation assays; artefactual incorporation of amines in cells and tissue homogenates; synthetic substrate systems; regulation of transglutaminase activities; strategies for probing transglutaminase-mediated events in biological systems; the blood clotting paradigm; transglutaminase and cell aging: the Ca2+-enriched human erythrocyte; transglutaminase and cell activation: the thrombin-stimulated human platelet and the fertilized sea urchin egg.