New chromogenic substrates for thrombin with increased specificity

Area of Science:

• Biochemistry
• Analytical Chemistry

Background:

• Specific chromogenic substrates are crucial for functional assays like photometric prothrombin time (PT) and activated partial thromboplastin time (APTT).
• Existing substrates may lack the high specificity required for accurate thrombin activity measurement in complex biological mixtures.

Purpose of the Study:

• To develop novel chromogenic peptide substrates with improved specificity for thrombin.
• To evaluate the utility of these new substrates in functional coagulation assays.

Main Methods:

• Synthesized tripeptide sequences selective for thrombin coupled to 5-amino-2-nitro benzoic acid (ANBA) derivatives.
• Compared hydrolysis rates and Michaelis-Menten (KM) values of ANBA-based substrates with para-nitroanilide (pNA) substrates using thrombin and other proteases (kallikrein, plasmin, factor Xa).

Main Results:

• ANBA-substituted chromogenic substrates demonstrated significantly decreased hydrolysis rates by kallikrein, plasmin, and factor Xa compared to pNA-based substrates.
• These ANBA peptide substrates remained sensitive to thrombin, with KM values comparable to pNA-peptides.
• The modified substrates showed potential for selective thrombin detection.

Conclusions:

• Coupling thrombin-selective tripeptides to ANBA derivatives enhances chromogenic substrate specificity.
• ANBA peptide substrates offer a promising tool for selective thrombin measurement in the presence of other proteases.
• These substrates are suitable for colorimetric determination of PT and APTT assays.