Biochemical characterization of a thrombin inhibitor from the bloodsucking bug Dipetalogaster maximus.
From the bloodsucking bug Dipetalogaster maximus, a protein with anticoagulant activity was isolated and biochemically characterized. The isolated protein, named dipetalogastin, possesses an average molecular mass of 11.8 kD. Its N-terminal sequence shows homology to rhodniin, a thrombin inhibitor isolated from the bug Rhodnius prolixus. The in vitro anticoagulant activity of dipetalogastin occurs via the inhibition of thrombin. The anticoagulant and thrombin inhibitory potency of dipetalogastin is comparable to that of recombinant hirudin. Its specific thrombin inhibitory activity is 9,300 antithrombin units/mg protein. Dipetalogastin forms only 1:1 molar complexes with thrombin. It is a tight-binding inhibitor of thrombin possessing a dissociation constant of 125 fM. It does not inhibit factor Xa or alpha-chymotrypsin and only weakly inhibits trypsin.
Lange
U
U
Research Unit Pharmacological Hemostaseology, Medical Faculty of the Friedrich Schiller University, Jena, Germany. lan@bug.mpg.uni-jena.de
Keilholz
W
W
Schaub
G A
GA
Landmann
H
H
Markwardt
F
F
Nowak
G
G
D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001780:Blood Coagulation Tests; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D010450:Endopeptidases / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D005170:Factor X / Q000037:antagonists & inhibitors; D005340:Fibrinogen / Q000187:drug effects / Q000378:metabolism; D006629:Hirudins / Q000378:metabolism / Q000494:pharmacology; D019476:Insect Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010314:Partial Thromboplastin Time; D011485:Protein Binding; D013270:Stomach; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013918:Thrombin Time; D014225:Triatominae / Q000737:chemistry*; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000378:metabolism
D000925:Anticoagulants; D004791:Enzyme Inhibitors; D006629:Hirudins; D019476:Insect Proteins; D014361:Trypsin Inhibitors; C407584:dipetalogastin protein, Dipetalogaster maximus; D005170:Factor X; D005340:Fibrinogen; D010450:Endopeptidases; D014357:Trypsin; D013917:Thrombin; C020097:ecarin