Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trypanosoma cruzi, a protozoan parasite, is the etiologic agent of American trypanosomiasis or Chagas' disease. Chagas' disease afflicts more than 24 million individuals in South and Central America producing a debilitating life-long disease. It is the leading cause of heart failure in many Latin American countries. Currently, there is no satisfactory treatment for this parasitic infection. Cruzain (also known as cruzipain, gp 57/51), the major cysteine protease present in T. cruzi, is critical for the development and survival of the parasite within the host cells, making this enzyme a target for potential trypanocidal drugs. Here we report the X-ray crystal structure of cruzain complexed with the potent inhibitor Z-Phe-Ala-fluoromethyl ketone. The structure was determined at 2.35 A (Rcryst = 0.15) by molecular replacement using a modified papain as the search model. The refined structure is compared to papain. Features which distinguish cruzain from papain are discussed since they may aid in the design of specificity inhibitors. Fluorescence microscopy shows that a biotinylated form of the bound inhibitor does not effectively reach host proteases in their lysosomal compartment, but is selectively taken up by the parasite. The inhibitor greatly reduces parasitemia in a cell culture system, without adverse effects to mammalian cells. This biological selectivity can be exploited, in conjunction with unique active site features revealed by the crystal structure, to develop chemotherapy for Chagas' disease.
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PMID:The crystal structure of cruzain: a therapeutic target for Chagas' disease. 770 73

Sulfinamide [RS(O)NH(2)] formation is known to occur upon exposure of cysteine residues to nitroxyl (HNO), which has received recent attention as a potential heart failure therapeutic. Because this modification can alter protein structure and function, we have examined the reactivity of sulfinamides in several systems, including a small organic molecule, peptides, and a protein. Although it has generally been assumed that this thiol to sulfinamide modification is irreversible, we show that sulfinamides can be reduced back to the free thiol in the presence of excess thiol at physiological pH and temperature. We have examined this sulfinamide reduction both in peptides, where a cyclic intermediate analogous to that proposed for asparagine deamidation reactions potentially can contribute, and in a small organic molecule, where the mechanism is restricted to a direct thiolysis. These studies suggest that the contribution from the cyclic intermediate becomes more important in environments with lower dielectric constants. In addition, although sulfinic acid [RS(O)OH] formation is observed upon prolonged incubations in water, reduction of sulfinamides is found to dominate in the presence of thiols. Finally, studies with the cysteine protease, papain, suggest that the reduction of sulfinamide to the free thiol is viable in a protein environment.
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PMID:Reactivity of nitroxyl-derived sulfinamides. 2257 Nov 65

Cystatin C (cys-C) is a small protein molecule (120 amino acid peptide chain, approximately 13kDa) produced by virtually all nucleated cells in the human body. It belongs to the family of papain-like cysteine proteases and its main biological role is the extracellular inhibition of cathepsins. It's near constant production rate, the fact that it is freely filtered from the glomerular membrane and then completely reabsorbed without being secreted from the proximal tubular cells, made it an almost perfect candidate for estimating renal function. The strong correlation between chronic kidney disease (CKD) and cardiovascular disease (CVD) along with the growing understanding of the role of cysteinyl cathepsins in the pathophysiology of CVD inspired researchers to explore the potential association of cys-C with CVD. Throughout the spectrum of CVD (peripheral arterial disease, stroke, abdominal aortic aneurysm, heart failure, coronary artery disease) adverse outcomes and risk stratification have been associated with high plasma levels of cys-C. The exact mechanisms behind the observed correlations have not been comprehensively clarified. Plausible links between high cys-C levels and poor cardiovascular outcome could be impaired renal function, atherogenesis and inflammatory mediators, remodeling of myocardial tissue and others (genetic factors, aging and social habits). The scope of the present article is to systematically review the current knowledge about cys-C biochemistry, metabolism, methods of detection and quantification and pathophysiological associations with different aspects of CVD.
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PMID:Cystatin C: an emerging biomarker in cardiovascular disease. 2347 76

Nitroxyl (HNO), a potential heart failure therapeutic, is known to post-translationally modify cysteine residues. Among reactive nitrogen oxide species, the modification of cysteine residues to sulfinamides [RS(O)NH2] is unique to HNO. We have applied (15)N-edited (1)H NMR techniques to detect the HNO-induced thiol to sulfinamide modification in several small organic molecules, peptides, and the cysteine protease, papain. Relevant reactions of sulfinamides involve reduction to free thiols in the presence of excess thiol and hydrolysis to form sulfinic acids [RS(O)OH]. We have investigated sulfinamide hydrolysis at physiological pH and temperature. Studies with papain and a related model peptide containing the active site thiol suggest that sulfinamide hydrolysis can be enhanced in a protein environment. These findings are also supported by modeling studies. In addition, analysis of peptide sulfinamides at various pH values suggests that hydrolysis becomes more facile under acidic conditions.
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PMID:NMR detection and study of hydrolysis of HNO-derived sulfinamides. 2407 27