Comparative action of various kininogenases on crude horse plasma substrates.

This study focused on comparing the activity of various kininogenase enzymes, such as trypsin, plasmin, plasma kallikrein, and heated Bothrops venom, with respect to their substrates: fresh, heated, and heat-acid-denatured horse plasma, to understand their role in the kinin system, particularly emphasizing the significance of plasmin.

Overview of Study Findings

• The study found that among the tested enzymes, Bothrops venom kininogenase exhibited the highest activity on fresh horse plasma. Meanwhile, plasmin and trypsin showed equal activity levels, with plasma kallikrein’s activity being half that of plasmin on the same substrates.
• Plasmin and trypsin released more kinin (a peptide that leads to blood vessel dilation) from heat-treated plasma compared to fresh plasma. In contrast, kallikrein released only half the amount of kinin it usually liberates from fresh plasma.
• When applied to heat-acid-denatured plasma, plasmin, trypsin, and Bothrops kininogenase came out with equal activity. However, the activity of plasma kallikrein was significantly reduced, being only one tenth of that of plasmin or trypsin.
• Another notable observation was that none of the enzymes under study released additional kinin from any of the substrates upon activation with trypsin or plasmin. Post plasma kallikrein activation, plasmin, trypsin, and Bothrops kininogenase, all released more kinin from the tested substrates.

Significance of Results and Future Implications

• The research’s findings clearly imply the potential prominence of plasmin in the kinin system, an enzyme system that regulates blood pressure.
• The study concluded that plasmin could replace trypsin in the determination of plasma kininogen through the method suggested by Diniz et al.13, reflecting the role plasmin could play in diagnostic processes and possibly future therapeutic applications.
• With a clearer understanding of these enzymatic activities, researchers could potentially exploit them in drug development, specifically in combatting conditions related to blood pressure and cardiovascular health.