Plasma Levels of Protein S, Protein C, and Factor X: Effects of Sex, Hormonal State and Age

1995 ◽  
Vol 74 (05) ◽  
pp. 1271-1275 ◽  
Author(s):  
C M A Henkens ◽  
V J J Bom ◽  
W van der Schaaf ◽  
P M Pelsma ◽  
C Th Smit Sibinga ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Postmenopausal Women ◽  
Protein C ◽  
Blood Donors ◽  
Premenopausal Women ◽  
Protein S ◽  
The Other ◽  
Factor X ◽  
Normal Ranges

SummaryWe measured total and free protein S (PS), protein C (PC) and factor X (FX) in 393 healthy blood donors to assess differences in relation to sex, hormonal state and age. All measured proteins were lower in women as compared to men, as were levels in premenopausal women as compared to postmenopausal women. Multiple regression analysis showed that both age and subgroup (men, pre- and postmenopausal women) were of significance for the levels of total and free PS and PC, the subgroup effect being caused by the differences between the premenopausal women and the other groups. This indicates a role of sex-hormones, most likely estrogens, in the regulation of levels of pro- and anticoagulant factors under physiologic conditions. These differences should be taken into account in daily clinical practice and may necessitate different normal ranges for men, pre- and postmenopausal women.

The Mechanism of Protein S as An Anticoagulant Independent of Activated Protein C.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3186-3186
Author(s):  
Rinku Majumder
Keyword(s):  
Venous Thrombosis ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Factor X ◽  
Protein S Deficiency ◽  
Factor Ixa ◽  
S Deficiency ◽  
Factor X Activation

Abstract 3186 Poster Board III-123 Thrombosis is a serious problem in the United States. The overall estimated incidence (annual occurrence) of deep venous thrombosis is 1 episode for every 1000 persons. Protein S, a vitamin K-dependent protein, is one of the natural anticoagulants found in the blood. Deficiency of protein S is most common protein deficiencies associated with familial venous thrombosis There are studies that suggest an association between arterial thrombosis (stroke, heart attack) in patients with protein S deficiency. At this time, the exact role of protein S deficiency and its relative importance in arterial disease is still being explored by physicians and scientists. Protein S is known as a non-enzymatic cofactor of activated Protein C in the inactivation of factors Va and VIIIa, as part of a negative feedback loop to regulate blood coagulation. Plasma coagulation assays in the absence of activated protein C suggest that Protein S may have other anticoagulant role(s). For example, it has been suggested that Protein S down-regulates thrombin generation by stimulating FXa inhibition by the tissue factor pathway inhibitor (Rosing, J., et al., Thromb Res, 2008. 122 Suppl 1: p. S60-3). It has also been proposed that protein S can directly inhibit the intrinsic Xase complex (Takeyama, M., et al.. Br J Haematol, 2008. 143(3): p. 409-20). But the exact mechanism of how Protein S exerts its anticoagulant effect on factor IXa/VIIIa complex is still unclear. In order to determine the role of Protein S as an anticoagulant in the intrinsic Xase Complex, we have used C6PS (a small six carbon chain synthetic Phosphatidylserine (PS) molecule) that does not occur in vivo, but has been used as a powerful tool in demonstrating the regulation of both factors Xa and Va by binding of molecular PS. Soluble lipid binding can offer invaluable insights into events that would be next to impossible to document on a membrane surface which is complicated as it has surface condensation effect and allosteric effects of different factors. We focus here on the conformation changes of the proteins by using C6PS as a tool. We have determined the binding of Protein S with C6PS by using tryptophan fluorescence and observed a stoichiometric Kd of ∼180 μM.We checked for micelles formation under each experimental condition. We have also determined the direct binding of factor IXa with Protein S by using DEGR-IXa ((5-(dimethylamino)1-naphthalenesulfonyl]-glutamylglycylarginyl chloromethyl ketone) in the presence and absence of C6PS. Our results show that the affinity of binding of DEGR-IXa to Protein S in the presence of C6PS is ∼22 fold tighter (Kd ∼15 nM compared to 324 nM) than without C6PS. We also measured the rate of factor X activation by factor IXa with the addition of increasing concentration of C6PS in the presence and absence of Protein S. We observed that Protein S decreased factor IXa mediated factor X activation by 14 fold. We had previously shown that apparent Kd of factor IXa binding to C6PS during factor X activation was ∼125 μM. But addition of Protein S had an effect on the apparent Kd as it increased to 700 μM indicating the affinity of factor IXa towards C6PS was decreased with the addition of Protein S during factor X activation. From these data we can speculate that Protein S induces a conformational change in factor IXa in the presence of C6PS which may affect the interaction of factor IXa with factor VIIIa, thus affecting the intrinsic Xase complex. Using this useful tool (C6PS), we will characterize the anticoagulant role of Protein S in the intrinsic Xase complex which in turn will give us some insights into this important protein which is a crucial target for therapeutic drugs for venous thrombosis. Disclosures No relevant conflicts of interest to declare.

scholarly journals The functional significance of the autolysis loop in protein C and activated protein C

2005 ◽  
Vol 94 (07) ◽  
pp. 60-68 ◽  
Author(s):  
Likui Yang ◽  
Chandrashekhara Manithody ◽  
Alireza R. Rezaie
Keyword(s):  
Half Life ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Factor X ◽  
Binding Studies ◽  
Factor Va ◽  
Direct Binding ◽  
Anticoagulant Function

SummaryThe autolysis loop of activated protein C (APC) is five residues longer than the autolysis loop of other vitamin K-dependent coagulation proteases. To investigate the role of this loop in the zymogenic and anticoagulant properties of the molecule, a protein C mutant was constructed in which the autolysis loop of the protein was replaced with the corresponding loop of factor X. The protein C mutant was activated by thrombin with ~5-fold higher rate in the presence of Ca2+. Both kinetics and direct binding studies revealed that the Ca2+ affinity of the mutant has been impaired ∼3-fold. The result of a factorVa degradation assay revealed that the anticoagulant function of the mutant has been improved 4–5-fold in the absence but not in the presence of protein S. The improvement was due to a better recognition of both the P1-Arg506 and P1-Arg306 cleavage sites by the mutant protease. However, the plasma half-life of the mutant was markedly shortened due to faster inactivation by plasma serpins. These results suggest that the autolysis loop of protein C is critical for the Ca2+-dependence of activation by thrombin. Moreover, a longer autolysis loop in APC is not optimal for interaction with factor Va in the absence of protein S, but it contributes to the lack of serpin reactivity and longer half-life of the protease in plasma.

The Influence of Insulin, ß-Estradiol, Dexamethasone and Thyroid Hormone on the Secretion of Coagulant and Anticoagulant Proteins by HepG2 Cells

1995 ◽  
Vol 74 (02) ◽  
pp. 686-692 ◽  
Author(s):  
René W L M Niessen ◽  
Birgit A Pfaffendorf ◽  
Augueste Sturk ◽  
Roy J Lamping ◽  
Marianne C L Schaap ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Protein C ◽  
Protein Production ◽  
Culture Medium ◽  
Protein S ◽  
Cell Protein ◽  
Hepatoma Cell Line ◽  
Factor X ◽  
Factor Ii ◽  
At Iii

SummaryAs a basis for regulatory studies on the influence of hormones on (anti)coagulant protein production by hepatocytes, we examined the amounts of the plasma proteins antithrombin III (AT III), protein C, protein S, factor II, factor X, fibrinogen, and prealbumin produced by the hepatoma cell line HepG2, into the culture medium, in the absence and presence of insulin, β-estradiol, dexamethasone and thyroid hormone. Without hormones these cells produced large amounts of fibrinogen (2,452 ± 501 ng/mg cell protein), AT III (447 ± 16 ng/mg cell protein) and factor II (464 ± 31 ng/mg cell protein) and only small amounts of protein C (50 ± 7 ng/mg cell protein) and factor X (55 ± 5 ng/mg cell protein). Thyroid hormone had a slight but significant effect on the enrichment in the culture medium of the anticoagulant protein AT III (1.34-fold) but not on protein C (0.96-fold) and protein S (0.91-fold). This hormone also significantly increased the amounts of the coagulant proteins factor II (1.28-fold), factor X (1.45-fold) and fibrinogen (2.17-fold). Insulin had an overall stimulating effect on the amounts of all the proteins that were investigated. Neither dexamethasone nor ß-estradiol administration did substantially change the amounts of these proteins.We conclude that the HepG2 cell is a useful tool to study the hormonal regulation of the production of (anti)coagulant proteins. We studied the overall process of protein production, i.e., the amounts of proteins produced into the culture medium. Detailed studies have to be performed to establish the specific hormonal effects on the underlying processes, e.g., transcription, translation, cellular processing and transport, and secretion.

PENGARUH KUALITAS PRODUK DAN RELIGIUSITAS TERHADAP KEPUTUSAN NASABAH PRODUK SIMPANAN PADA BSM CABANG PURWOKERTO

2017 ◽  
Vol 4 (1) ◽  
pp. 189-215
Author(s):  
Yoiz Shofwa Shafrani
Keyword(s):  
Regression Analysis ◽  
Product Quality ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Analytical Tool ◽  
The Other ◽  
Financial Assets ◽  
Islamic Bank

Perkembangan dunia perbankan syariah tidak lepas dari peran para nasabah yang memberikan kepercayaan terhadap pihak perbankan untuk penyimpanan asset keuangannya. Faktanya banyak kelompok nasabah yang memutuskan untuk menjadi nasabah di perbankan syariah karena faktor religiusitasnya. Faktor lain yang dapat ikut mempengaruhi keputusan nasabah adalah kualitas produk. Di mana kualitas produk merupakan karakteristik yang melekat dari suatu produk. Kemungkinan yang terjadi bahwa kebanyakan nasabah pada perbankan syariah juga masih merupakan nasabah perbankan konvensional.Tujuan yang ingin dicapai dalam penelitian ini adalah untuk mengetahui pengaruh kualitas produk dan tingkat religiusitas nasabah terhadap keputusan nasabah untuk menyimpan dananya atau tidak di BSM Cabang Purwokerto. Alat analisis yang digunakan adalah analisis regresi linier berganda, dengan jumlah sampel 100 nasabah. Diperoleh hasil Y = 5,046 + 0,101X1 + 0,218X2. Berdasarkan uji F yang sudah dilakukan maka dapat diketahui bahwa variabel kualitas produk dan religiusitas secara bersama – sama berpengaruh terhadap keputusan nasabah untuk menyimpan dananya di BSM Cabang Purwokerto. Berdasarkan uji t yang sudah dilakukan dapat diketahui bahwa secara partial baik variabel kualitas produk maupun variabel religiusitas berpengaruh terhadap keputusan nasabah untuk menyimpan dananya di BSM Cabang Purwokerto. The progress of the Islamic bank cannot be separated from the role of its customers who give trust to the bank to deposit their financial assets. It is a fact many groups of customers decide to be the customers of the Islamic bank because of their religiosity. The other influences factor of a customer’s decision is the quality of the product. The aim of this research was to determine the effect of product quality and level of customers’ religiosity towards customers’ decision whether to keep their funds in Syariah Mandiri Bank, Branch of Purwokerto, or not. The analytical tool used was multiple linear regression analysis, with a sample of 100 customers. The results indicate Y = 5,046 + 0,101X1 + 0,218X2. Based on F, it can be seen that both variables of product quality and religiosity simultanously affect the customers’ decision to keep theirfunds in BSM Branch of Purwokerto. Based on t test, it can be seen that independently, either variable of product quality or variables of religiosityinfluences the customers’ decision to keep their funds in BSM Branch of Purwokerto.

scholarly journals Serum osteocalcin concentrations in relation to glucose and lipid metabolism in Chinese individuals

2009 ◽  
Vol 161 (5) ◽  
pp. 723-729 ◽  
Author(s):  
Mi Zhou ◽  
Xiaojing Ma ◽  
Huating Li ◽  
Xiaoping Pan ◽  
Junling Tang ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Lipid Metabolism ◽  
Glucose Tolerance ◽  
Lipid Profile ◽  
Postmenopausal Women ◽  
Multiple Logistic Regression Analysis ◽  
Premenopausal Women ◽  
Diabetic Patients ◽  
Model Assessment ◽  
Serum Osteocalcin

ObjectivesOsteocalcin, a bone-derived protein, has recently been reported to affect energy metabolism. We investigated the relationship between serum osteocalcin and parameters of adiposity, glucose tolerance, and lipid profile in Chinese subjects.MethodsSerum osteocalcin was measured by electrochemiluminescence immunoassay in 254 men (128 with newly diagnosed type 2 diabetes mellitus (T2DM) and 126 with normal glucose tolerance (NGT)), 66 premenopausal women (33 with T2DM and 33 with NGT) as well as 180 postmenopausal women (92 with T2DM and 88 with NGT). Their associations with parameters of adiposity, glucose tolerance, and lipid profile were examined.ResultsSerum osteocalcin concentrations in diabetic patients were significantly lower than those in NGT subjects after adjusted for age, gender, and body mass index (P=0.003). Postmenopausal women had higher osteocalcin concentrations than premenopausal women and men (both P<0.001). Multiple stepwise regression analysis showed that age, %fat, high-density lipoprotein cholesterol, fasting plasma glucose, and fasting serum insulin were independently associated with osteocalcin in men (P<0.05). Age and HbA1c were independently correlated with osteocalcin in postmenopausal women. Besides age and HbA1c, serum triglyceride was also an independent factor influencing osteocalcin in premenopausal women. In addition, osteocalcin was also positively associated with homeostasis model assessment of β-cell function. Furthermore, multiple logistic regression analysis demonstrated that osteocalcin was independently associated with T2DM.ConclusionsSerum osteocalcin was closely associated with not only fat and glucose metabolism but also with lipid metabolism.

Diabetes does not influence activation of coagulation, fibrinolysis or anticoagulant pathways in Gram-negative sepsis (melioidosis)

2011 ◽  
Vol 106 (12) ◽  
pp. 1139-1148 ◽  
Author(s):  
Joost Meijers ◽  
Rapeephan Maude ◽  
Direk Limmathurotsakul ◽  
Nicholas Day ◽  
Sharon Peacock ◽  
...  
Keyword(s):  
Protein C ◽  
Burkholderia Pseudomallei ◽  
Blood Donors ◽  
Protein S ◽  
Admission Diagnosis ◽  
Procoagulant Effect ◽  
Multiple Abnormalities ◽  
The Impact ◽  
D Dimer

SummaryDiabetes is associated with a disturbance of the haemostatic balance and is an important risk factor for sepsis, but the influence of diabetes on the pathogenesis of sepsis remains unclear. Melioidosis (Burkholderia pseudomallei infection) is a common cause of community-acquired sepsis in Southeast Asia and northern Australia. We sought to investigate the impact of pre-existing diabetes on the coagulation and fibrinolytic systems during sepsis caused by B. pseudomallei. We recruited a cohort of 44 patients (34 with diabetes and 10 without diabetes) with culture-proven melioidosis. Diabetes was defined as a pre-admission diagnosis of diabetes or an HbA1c>7.8% at enrolment. Thirty healthy blood donors and 52 otherwise healthy diabetes patients served as controls. Citrated plasma was collected from all subjects; additionally in melioidosis patients follow-up specimens were collected seven and ≥28 days after enrolment where possible. Relative to uninfected healthy controls, diabetes per se (i.e. in the absence of infection) was Characterised by a procoagulant effect. Melioidosis was associated with activation of coagulation (thrombin-antithrombin complexes (TAT), prothrombin fragment F1+2 and fibrinogen concentrations were elevated; PT and PTT prolonged), suppression of anti-coagulation (antithrombin, protein C, total and free protein S levels were depressed) and abnormalities of fibrinolysis (D-dimer and plasmin-antiplasmin complex [PAP] were elevated). Remarkably, none of these haemostatic alterations were influenced by pre-existing diabetes. In conclusion, although diabetes is associated with multiple abnormalities of coagulation, anticoagulation and fibrinolysis, these changes are not detectable when superimposed on the background of larger abnormalities attributable to B. pseudomallei sepsis.

A Mutation of the Active Protein S Gene Leading to an EGF1-Lacking Protein in a Family With Qualitative (Type II) Deficiency

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4608-4615 ◽  
Author(s):  
C. Leroy-Matheron ◽  
M. Gouault-Heilmann ◽  
M. Aiach ◽  
S. Gandrille
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Genomic Analysis ◽  
Protein S ◽  
The Other ◽  
Type Ii ◽  
Active Protein ◽  
Reducing Conditions ◽  
Cofactor Activity ◽  
Inactive Protein

Abstract The genomic analysis of a 70-year-old man with recurrent deep venous thrombosis having a protein S (PS)-deficient phenotype corresponding to both type III and type II evidenced two different mutations: a +5 g→a mutation in the donor splice site of intron e (ivs e) and a ser 460 to Pro mutation. The propositus' son, who had a type II PS deficiency phenotype, only bore the ivs e +5 g→a mutation. The study of platelet PS mRNA prepared from this subject showed that the ivs e, +5 g→a mutation led to the generation of two abnormal transcripts, one lacking exon 5 and the other lacking exons 5 and 6. The presence of an additional PS band with a decreased molecular mass on immunoblots performed in reducing conditions suggested the presence of truncated PS lacking EGF1 (encoded by exon 5). Two monoclonal antibodies (MoAbs) were used to further characterize the nonfunctional plasma PS. Comparison of PS levels measured with each of these MoAbs and PS levels in conventional assays was consistent with the presence of an abnormal inactive protein in the plasma of both patients bearing the ivs e, +5 g→a mutation, suggesting that variant PS lacking EGF1 is secreted but is devoid of activated protein C cofactor activity.

A Mutation of the Active Protein S Gene Leading to an EGF1-Lacking Protein in a Family With Qualitative (Type II) Deficiency

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4608-4615 ◽  
Author(s):  
C. Leroy-Matheron ◽  
M. Gouault-Heilmann ◽  
M. Aiach ◽  
S. Gandrille
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Genomic Analysis ◽  
Protein S ◽  
The Other ◽  
Type Ii ◽  
Active Protein ◽  
Reducing Conditions ◽  
Cofactor Activity ◽  
Inactive Protein

The genomic analysis of a 70-year-old man with recurrent deep venous thrombosis having a protein S (PS)-deficient phenotype corresponding to both type III and type II evidenced two different mutations: a +5 g→a mutation in the donor splice site of intron e (ivs e) and a ser 460 to Pro mutation. The propositus' son, who had a type II PS deficiency phenotype, only bore the ivs e +5 g→a mutation. The study of platelet PS mRNA prepared from this subject showed that the ivs e, +5 g→a mutation led to the generation of two abnormal transcripts, one lacking exon 5 and the other lacking exons 5 and 6. The presence of an additional PS band with a decreased molecular mass on immunoblots performed in reducing conditions suggested the presence of truncated PS lacking EGF1 (encoded by exon 5). Two monoclonal antibodies (MoAbs) were used to further characterize the nonfunctional plasma PS. Comparison of PS levels measured with each of these MoAbs and PS levels in conventional assays was consistent with the presence of an abnormal inactive protein in the plasma of both patients bearing the ivs e, +5 g→a mutation, suggesting that variant PS lacking EGF1 is secreted but is devoid of activated protein C cofactor activity.

scholarly journals Role of clinical and biochemical inflammation in structural progression of patients with psoriatic arthritis

RMD Open ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. e002038
Author(s):  
Carina Borst ◽  
Farideh Alasti ◽  
Josef S Smolen ◽  
Daniel Aletaha
Keyword(s):  
Logistic Regression ◽  
Regression Analysis ◽  
Psoriatic Arthritis ◽  
Radiographic Progression ◽  
Controlled Trial ◽  
The Other ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Structural Progression

ObjectiveTo determine the contribution of clinical and biochemical inflammation to structural progression of patients with psoriatic arthritis (PsA).MethodsWe analysed patients from the Infliximab Multinational Psoriatic Arthritis Controlled Trial 2 trial (infliximab vs placebo). We obtained total modified Sharp/van-der-Heijde Scores from baseline and year one images, and swollen joint counts (SJC) and levels of C reactive protein (CRP) throughout the second half of year 1 (5 measurements) from 74 placebo-treated patients. We computed radiographic progression, time-averaged SJC (taSJC) and CRP (taCRP) values and assessed their impact on structural progression by logistic regression analysis. We further categorised patients as ‘active’ (+) or ‘inactive’ (−) based on their taSJC (cut-off point: 2/66 joints) and taCRP (cut-off point: 0.5 mg/dL) and compared radiographic progression across three groups (double inactive, single active, double active).ResultsORs for progression were 1.24 (95 % CI 1.04 to 1.47; p=0.016) for taSJC and 6.08 (95 % CI 1.12 to 33.03; p=0.036) for taCRP. When predictors were dichotomised (+ vs −), differences were maintained between taSJC+ and taSJC− patients (1.05±3.21 and 0.56±2.30, respectively), as well as for taCRP+ vs taCRP− patients (1.14±3.23 and 0.05±2.37, respectively). Progression was intermediate in the presence of abnormalities of one but not the other inflammatory variable, indicating increasing radiographic progression with increasing inflammation (p=0.05).ConclusionIn patients with PsA, both clinical and biochemical inflammation have an impact on structural progression. Overall, progression is smallest in the absence of both clinical and biochemical inflammation, higher when either clinical or biochemical inflammation is present and highest with both clinical and biochemical inflammation.

scholarly journals Inhibition of the intrinsic factor X activating complex by protein S: evidence for a specific binding of protein S to factor VIII

Blood ◽  
1995 ◽  
Vol 86 (3) ◽  
pp. 1062-1071 ◽  
Author(s):  
SJ Koppelman ◽  
TM Hackeng ◽  
JJ Sixma ◽  
BN Bouma
Keyword(s):  
Factor Viii ◽  
Protein C ◽  
Intrinsic Factor ◽  
Activated Protein C ◽  
Protein S ◽  
Inhibitory Effect ◽  
Factor X ◽  
Ic50 Values ◽  
Factor X Activation ◽  
Factor X Activating Complex

Protein S is a vitamin K-dependent nonenzymatic anticoagulant protein that acts as a cofactor to activated protein C. Recently it was shown that protein S inhibits the prothrombinase reaction independent of activated protein C. In this study, we show that protein S can also inhibit the intrinsic factor X activation via a specific interaction with factor VIII. In the presence of endothelial cells, the intrinsic activation of factor X was inhibited by protein S with an IC50 value of 0.28 +/- 0.04 mumol/L corresponding to the plasma concentration of protein S. This inhibitory effect was even more pronounced when the intrinsic factor X activation was studied in the presence of activated platelets (IC50 = 0.15 +/- 0.02 mumol/L). When a nonlimiting concentration of phospholipid vesicles was used, the plasma concentration of protein S (300 nmol/L) inhibited the intrinsic factor X activation by 40%. Thrombin-cleaved protein S inhibited the endothelial cell-mediated factor X activation with an IC50 similar to that of native protein S (0.26 +/- 0.02 mumol/L). Protein S in complex with C4b-binding protein inhibited the endothelial cell-mediated factor X activation more potently than protein S alone (IC50 = 0.19 +/- 0.03 mumol/L). Using thrombin activated factor VIII, IC50 values of 0.53 +/- 0.09 mumol/L and 0.46 +/- 0.10 mumol/L were found for native protein S and thrombin-cleaved protein S, respectively. The possible interactions of protein S with factor IXa, phospholipids, and factor VIII were investigated. The enzymatic activity of factor IXa was not affected by protein S, and interaction of protein S with the phospholipid surface could not fully explain the inhibitory effect of protein S on the factor X activation. Using a solid-phase binding assay, we showed a specific, saturable, and reversible binding of protein S to factor VIII with a high affinity. The concentration of protein S where half-maximal binding was reached (B1/2max) was 0.41 +/- 0.06 mumol/L. A similar affinity was found for the interaction of thrombin-cleaved protein S with factor VIII (B1/2max = 0.40 +/- 0.04 mumol/L). The affinity of the complex protein S with C4B-binding protein appeared to be five times higher (B1/2max = 0.07 +/- 0.03 mumol/L). Because the affinities of the interaction of the different forms of protein S with factor VIII correspond to the IC50 values observed for the intrinsic factor X activating complex, the interaction of protein S with factor VIII may explain the inhibitory effect of protein S on the intrinsic factor X activating complex.(ABSTRACT TRUNCATED AT 400 WORDS)

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