[The critical role of the interaction of anion-binding thrombin exosite with complementary segment of the Aalpha-chain of fibrinogen in detecting high specificity of the enzyme].
Bovine fibrinogen N-terminal fragments were hydrolyzed by native alpha-thrombin and its nonclotting gamma-form with an additional disrupted anion-binding exosite (ABE). The susceptible bond 19-20 of the bovine fibrinogen A alpha-chain was found to be cleaved by alpha-thrombin more effectively than the gamma-form. The difference between the alpha- and gamma-forms disappeared as a result of the substrate site A alpha 37-54 breakdown and was not observed during the hydrolysis of nonspecific macromolecular substrates, such as chymotrypsinogen and insulin B-chain, the latter being hydrolyzed with equal inefficiency by alpha- and gamma-thrombins. The data obtained suggest that sequence 37-54 of the bovine fibrinogen A alpha-chain contains a thrombin recognition site (TRS) which corresponds to the enzyme ABE. Thus, the hypothesis about the existence of two types of high molecular weight thrombin substrates differing by the presence or absence of TRS previously postulated by the authors has been confirmed. The possibility of the catalytic process enhancement due to the ABE-TRS interaction is discussed.
Sereĭskaia
A A
AA
Smirnova
I V
IV
Karabut
L V
LV
Chetyrkina
S N
SN
D000595:Amino Acid Sequence; D000818:Animals; D000838:Anions / Q000378:metabolism*; D002384:Catalysis; D002417:Cattle; D002918:Chymotrypsin / Q000378:metabolism; D005340:Fibrinogen / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007328:Insulin / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D013379:Substrate Specificity; D013917:Thrombin / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
D000838:Anions; D007328:Insulin; D010446:Peptide Fragments; D005340:Fibrinogen; D002918:Chymotrypsin; D014357:Trypsin; D013917:Thrombin
Kriticheskaia rol' vzaimodeĭstviia anionsviazyvaiushchego dopolnitel'nogo trombina s komplementarnym emu uchastkom Aalpha-tsepi fibrinogena dlia proiavleniia vysokoĭ spetsifichnosti fermenta.