Protective Effect of Elastase Inhibition Against Myocardial Dysfunction and Injury Induced by Ischemia and Reperfusion in Isolated Rat Hearts

Utilization of the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold in the design of potent inhibitors of serine proteases: SAR studies using carboxylates

A series of carboxylate derivatives based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds has been synthesized and the inhibitory profile of these compounds toward human leukocyte elastase (HLE), cathepsin G (Cat G) and proteinase 3 (PR 3) was then determined. Most of the compounds were found to be potent, time-dependent inhibitors of elastase, with some of the compounds exhibiting k(inact)/K1 values as high as 4,928,300 M(-1) s(-1). The inhibitory potency of carboxylate derivatives based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide platform was found to be influenced by both the pKa and the inherent structure of the leaving group. Proper selection of the primary specificity group (R(I)) was found to lead to selective inhibition of HLE over Cat G, however, those compounds that inhibited HLE also inhibited PR 3, albeit less efficiently. The predictable mode of binding of these compounds suggests that, among closely-related serine proteases, highly selective inhibitors of a particular serine protease can be fashioned by exploiting subtle differences in their S' subsites. This study has also demonstrated that the degradative action of elastase on elastin can be abrogated in the presence of inhibitor 17.

Evidence for the presence of L-arginine-nitric oxide pathway in human red blood cells: relevance in the effects of red blood cells on platelet function

There is a renewed interest in the role of red blood cells (RBCs) in the regulation of vascular tone and platelet homeostasis. To examine whether human RBCs synthesize NO from L-arginine, which may mediate the antiplatelet effects of these cells, purified RBCs (10(7)-10(8)/ml) were incubated with [3H]L-arginine, and its conversion into [3H]L-citrulline determined. RBCs consistently converted [3H]L-arginine to [3H]L-citrulline in a Ca2+-dependent fashion, and this conversion was inhibited by two different specific NO synthase inhibitors. Suspension of RBCs (10(7)-10(8)/ml) reduced platelet aggregation, and the RBC-mediated inhibition of platelet aggregation was blocked by pretreatment of RBCs with NO synthase inhibitor and potentiated by pretreatment with superoxide dismutase. Release of serotonin by aggregating platelets also was inhibited in the presence of RBCs. Western analysis with a specific mouse monoclonal antibody provided direct evidence for the presence of human endothelium-type constitutive NO synthase with a molecular mass approximately 140 kDa in the RBC cytosol. These observations suggest that RBCs possess endothelium-type NO synthase and may regulate platelet function at least in part by in situ release of NO.

Use of the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds in the design of potent inhibitors of serine proteinases

The attachment of a phosphate leaving group to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide and isothiazolidin-3-one 1,1 dioxide scaffolds was found to yield highly potent, time-dependent inhibitors of human leukocyte elastase (HLE).

Inhibition of human leukocyte proteinase 3 by a novel recombinant serine proteinase inhibitor (LEX032)

The interaction of a bioengineered serpin (LEX032) with human leukocyte proteinase 3 (PR 3) has been investigated. LEX032 was found to be a time-dependent inhibitor of PR 3, forming a highly-stable enzyme-inhibitor complex (Ki 12 nM).