Biomaterial Database

Spectral changes in bovine factor X associated with activation by the venom coagulant protein of Vipera russelli. 1976

B Furie, and B C Furie

Bovine Factor X is a zymogen involved in blood coagulation that is converted to activated Factor X in the presence of Ca(II) by the coagulant protein of Russell's viper venom. To monitor structural transitions in Factor X during conversion to activated Factor X, the ultraviolet absorption, fluorescence emission, and circular dichroism spectra of activated Factor X and Factor X were compared. The ultraviolet absorption difference spectrum in the aromatic region comparing activated Factor X and Factor X indicates minima at 292.5, 285, and 278 nm and a small maximum at 305 nm; these differences are due to tryptophan and tyrosine perturbations. The activation of Factor X at 25 degrees in the presence of 8.3 mM CaCl2 with the use of Factor X:venom coagulant protein in molar rations of 1500:1 yielded a time-dependent increase in this spectrum which was linear for about 60 min and which temporally paralleled the development of activated Factor X activity. The binding of Ca(II) to factor X or activated Factor X is associated with a red-shifted tryptophan difference spectrum; however, this perturbation appears to make only a small contribution to the total perturbation observed during Factor X activation. Solvent perturbation studies in 20% glycerol suggest that an average of 3.1 tryptophan residues and 9.0 tyrosine residues are exposed to solvent in Factor X in 8.3 mM CaCl2 at pH 7.4; an additional 0.5 tryptophan residue and tyrosine reside become exposed to solvent during activation of Factor X in 8.3 mM CaCl2. The activation of Factor X by the venom coagulant protein is associated with a small red shift in the intrinsic tryptophan fluorescence emission spectrum. Far- and near-ultraviolet circular dichroism spectroscopy detected no difference between Factor X and activated Factor X. In summary, the activation of Factor X to activated Factor X appears associated with exposure of tryptophan and tyrosine side chains previously buried within the protein and with minimal changes in the secondary structur. These results suggest that conversion of Factor X to activated Factor X involves functionally important, but structurally subtle, changes in the three-dimentional structure.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D005170	Factor X	Storage-stable glycoprotein blood coagulation factor that can be activated to factor Xa by both the intrinsic and extrinsic pathways. A deficiency of factor X, sometimes called Stuart-Prower factor deficiency, may lead to a systemic coagulation disorder.	Autoprothrombin III,Coagulation Factor X,Stuart Factor,Stuart-Prower Factor,Blood Coagulation Factor X,Factor 10,Factor Ten,Stuart Prower Factor,Factor X, Coagulation
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D012910	Snake Venoms	Solutions or mixtures of toxic and nontoxic substances elaborated by snake (Ophidia) salivary glands (Duvernoy's gland) for the purpose of killing prey or disabling predators and delivered by grooved or hollow fangs. They usually contain enzymes, toxins, and other factors.	Duvernoy's Gland Secretion,Duvernoy's Secretion,Snake Toxin,Snake Toxins,Snake Venom,Duvernoy Gland Secretion,Duvernoy Secretion,Duvernoys Gland Secretion,Duvernoys Secretion,Secretion, Duvernoy's,Secretion, Duvernoy's Gland,Toxin, Snake,Venom, Snake
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D013056	Spectrophotometry, Ultraviolet	Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Ultraviolet Spectrophotometry