Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A low molecular weight serine protease inhibitor, named trypstatin, was purified from rat peritoneal mast cells. It is a single polypeptide with 61 amino acid residues and an Mr of 6610. Trypstatin markedly inhibits blood coagulation factor Xa (Ki = 1.2 x 10(-10) M) and tryptase (Ki = 3.6 x 10(-10) M) from rat mast cells, which have activities that convert prothrombin to thrombin. It also inhibits porcine pancreatic trypsin (Ki = 1.4 x 10(-8) M) and chymase (Ki = 2.4 x 10(-8) M) from rat mast cells, but not papain, alpha-thrombin, or porcine pancreatic elastase. Trypstatin forms a complex in a molar ratio of 1:1 with trypsin and one subunit of tryptase. The complete amino acid sequence of this inhibitor was determined and compared with those of Kunitz-type inhibitors. Trypstatin has a high degree of sequence homology with human and bovine inter-alpha-trypsin inhibitors, A4(751) Alzheimer's disease amyloid protein precursor, and basic pancreatic trypsin inhibitor. However, unlike other known Kunitz-type protease inhibitors, it inhibits factor Xa most strongly.
 ...
PMID:Kunitz-type protease inhibitor found in rat mast cells. Purification, properties, and amino acid sequence. 326 66

Bikunin is a plasma proteinase inhibitor that has received little attention in the past, probably because its activity towards various proteinases was found to be relatively weak in early work. It was recently discovered, however, that bikunin effectively inhibits a proteinase that seems to be involved in the metastasis of tumour cells--cell surface plasmin--and that a fragment of bikunin inhibits two proteinases of the coagulation pathway--factor Xa and kallikrein. Furthermore, it has been found that bikunin has other properties, such as the ability to modulate cell growth and to block cellular calcium uptake. Most of the bikunin in the blood occurs as a covalently linked subunit of the proteins pre- and inter-alpha-inhibitor. In this form bikunin lacks some of its known activities, and there is evidence that its release by partial proteolytic degradation may function as a regulatory mechanism. Although the physiological function of bikunin still remains to be established, current data suggest that this protein plays a role in inflammation. Further studies could therefore lead to results of therapeutical value.
 ...
PMID:Bikunin--not just a plasma proteinase inhibitor. 1068 49

Factor XII Tenri (Y34C), a rare cross-reacting material (CRM)-negative factor XII deficiency, was identified in a 71-yr-old Japanese woman with angina pectoris. In the patient's plasma, factor XII activity and antigen levels were only 1.6% and 5.0%, respectively, of those seen in a normal subject. Immunoblot analysis showed that the secreted factor XII Tenri existed not only as a monomer (76 kDa), but also in complexes with apparent molecular weights of approximately 115, 140, 190, 215, and 225 kDa. After reduction with 2-mercaptoethanol, the factor XII Tenri contained in the complexes was completely converted to monomeric form on immunoblot patterns. It appeared that some of the secreted factor XII Tenri formed several types of disulfide-linked complexes, including a factor XII-alpha1-microglobulin complex, through a newly generated Cys residue. The monomeric form of factor XII Tenri, like normal factor XII, was degraded into 2 major fragments with molecular weights of approximately 45 kDa and 30 kDa following mixing with activated partial-thromboplastin-time measuring reagent (cephalin and ellagic acid), whereas the factor XII Tenri that formed the complexes was not. This indicates that the factor XII Tenri present in disulfide-linked complexes with other proteins (and itself) is not converted to active forms, suggesting that attached proteins obstruct or delay the activation of factor XII via an inhibition of its binding to a negatively charged surface in vitro.
 ...
PMID:Characterization of factor XII Tenri, a rare CRM-negative factor XII deficiency. 1522 38