Factor X activating enzyme from Russell's viper venom: isolation and characterization

Area of Science:

• Biochemistry
• Proteomics
• Enzymology

Background:

• Russell's viper venom contains potent procoagulant enzymes.
• Understanding these enzymes is crucial for hemostasis research and potential therapeutic applications.

Purpose of the Study:

• To purify and characterize the Russell's viper venom protease responsible for activating Factor X, Factor IX, and Protein C.
• To elucidate the enzyme's molecular structure and specificity.

Main Methods:

• Purification using Sephadex G-150 gel filtration and QAE-Sephadex A-50 ion-exchange chromatography.
• Molecular weight determination via SDS-PAGE and sedimentation equilibrium.
• Analysis of subunit composition and amino-terminal sequences.
• Carbohydrate content analysis.

Main Results:

• The purified protease exhibited a molecular weight of 79,000 Da and consisted of a heavy chain (59,000 Da) and a light chain (18,000-20,000 Da).
• The heavy chain showed heterogeneous amino-terminal residues (Ile, Val, Ser), while the light chain had a Val-Leu-Asp sequence.
• The enzyme contained 13% carbohydrate, primarily on the heavy chain.
• No esterase activity or inhibition by diisopropyl phosphorofluoridate indicated high specificity.

Conclusions:

• The Russell's viper venom factor X activator is a specific protease.
• It is a heterodimer composed of disulfide-linked heavy and light chains.
• The enzyme's structure and composition contribute to its potent procoagulant activity.