Takayuki Imamura

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We have established a large-scale manufacturing system to produce recombinant human alpha-thrombin. In this system, a high yield of alpha-thrombin is prepared from prethrombin-2 activated by recombinant ecarin. We produced human prethrombin-2 using mouse myeloma cells and an expression plasmid carrying the chicken beta-actin promoter and mutant(More)
The inhibition of thrombin is one of the important treatments of pathological blood clot formation. Variegin, isolated from the tropical bont tick, is a novel molecule exhibiting a unique 'two-modes' inhibitory property on thrombin active site (competitive before cleavage, noncompetitive after cleavage). For the better understanding of its function, we have(More)
Fatty acid compositions of phosphatidyl ethanolamine and phosphatidyl choline extracted from the guinea pig Harderian gland were examined by gas chromatography and gas chromatography-mass spectrometry. Oleic acid was the major component of both phospholipids, but a large amount of saturated branched chain fatty acids was found: 34.5% in phosphatidyl(More)
BACKGROUND In thoracic surgery, although infrequent, we encounter unexpected damage to the pulmonary artery (PA). In the present study, we evaluated the hemostatic efficacy of a newly developed fibrin-based sheet material, thrombin sheet, coupled with liquid fibrinogen (TSF), in an experimental model of PA hemorrhage. METHODS Female beagles (n = 8) were(More)
Aprotinin is a polypeptide composed of 58 amino acid residues and has a molecular weight of 6512Da. The 58 amino acid residues are arranged in a single polypeptide chain, which is cross-linked by three disulfide bridges and folded to form a pear-shaped molecule. To express recombinant aprotinin in Saccharomyces cerevisiae, a synthetic gene encoding(More)
Porcine liver aminopeptidase was inactivated by various sulfhydryl-reactive reagents, whose inactivation rates were in the order: p-chloromercuribenzoate(PCMB) greater than HgCl2 greater than 2,2'-dithiodipyridine greater than 5,5'-dithiobis(2-nitrobenzoic acid)(DTNB). The processes of inactivation by these reagents did not follow pseudo-first-order(More)
In this study, we established stable cell lines producing 1.5 mg/mL recombinant human prothrombin in 400-L fed-batch culture, using CHO DG44 cells as a host cell line. And we also established a recombinant human α-thrombin purification process that produces a purified product suitable for use as a biopharmaceutical, by using recombinant ecarin from CHO DG44(More)
An aminopeptidase was purified about 700-fold from porcine liver homogenate by ammonium sulfate fractionation and a series of column chromatographies on DEAE-cellulose, Sephadex G-150, DEAE-Sepharose, and hydroxyapatite. The purified enzyme had a specific activity of 4.6 mumol X min-1 X mg-1 using L-leucine beta-naphthylamide as the substrate. The molecular(More)
Fibrinogen is a large and complex glycoprotein containing two sets of each of three different chains (α, β and γ). There have been no reports of high-level expression of fibrinogen at commercial levels using mammalian cultured cells such as CHO cells because of the difficulty in highly expressing a protein with such a complex structure. We achieved(More)