Glycosaminoglycan-mediated leuserpin-2/thrombin interaction. Structure-function relationships.

Two recently identified structural elements important for glycosaminoglycan-mediated activation of human leuserpin-2 (hLS2) were investigated in detail by functional analysis of variants secreted by transiently transfected COS cells. Highly specific requirements with respect to the nature of the involved amino acids as well as to their spatial arrangements were found to be crucial for efficient activation of hLS2 by dermatan sulfate. In contrast, binding and activation of hLS2 by heparin seem to be determined mainly by the positive charge density of the involved inhibitor segment.

On the activation of human leuserpin-2, a thrombin inhibitor, by glycosaminoglycans.

Human leuserpin-2 (hLS2) cDNA variants generated by site-directed mutagenesis were expressed in a transient COS cell system. Functional analysis of the mutants revealed two regions in the NH2-terminal half of hLS2 which are essential for glycosaminoglycan-enhanced thrombin inhibition by hLS2. One of these regions, which encompasses a dimeric structure enriched in basic amino acids, is required for both glycosaminoglycan binding and glycosaminoglycan-mediated acceleration of thrombin inhibition.