Analysis Biomolecular Interactions of Single‐Domain Antibodies (VHHs) with PN‐1 by BLI (CAT#: STEM-MB-0111-CJ)

Introduction

Protease nexin‐1 (PN‐1) belongs to a family of structurally related proteins known as inhibitors of serine protease or serpins, which can be found in most organisms. Serpins use their reactive center loops (RCL) to target the active site of serine proteases, driving the complex into a suicide substrate inhibition mechanism. This leads to inactivation of the protease and often rapid clearance via scavenger receptors.

Phylogenetically, PN‐1 is most closely related to plasminogen activator inhibitor 1 (PAI‐1) with 41% shared sequence. PN‐1 is undetectable in the circulating blood, but is present in circulating cells (monocytes and platelets) and vascular cells. PN‐1 is secreted during platelet activation and efficiently inhibits thrombin, the key enzyme of the coagulation cascade which catalyzes fibrin formation. Besides thrombin, PN‐1 inhibits several other serine proteases, albeit much less efficiently, such as trypsin, tissue‐type plasminogen activator, urokinase‐type plasminogen activator (u‐PA), plasmin, factor Xa, factor XIa, activated protein C, and factor VII activating protease. Its physiological role extends to several processes, like coagulation, fibrinolysis and tissue remodelling.