Abelardo M Silva

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The T = 3 capsid of southern bean mosaic virus is analyzed in detail. The beta-sheets of the beta-barrel folding motif that form the subunits show a high degree of twist, generated by several beta-bulges. Only 34 water molecules were identified in association with the three quasi-equivalent subunits, most of them on the external viral surface. Subunit(More)
Plasmodium falciparum is the major causative agent of malaria, a disease of worldwide importance. Resistance to current drugs such as chloroquine and mefloquine is spreading at an alarming rate, and our antimalarial armamentarium is almost depleted. The malarial parasite encodes two homologous aspartic proteases, plasmepsins I and II, which are essential(More)
Malaria remains a human disease of global significance and a major cause of high infant mortality in endemic nations. Parasites of the genus Plasmodium cause the disease by degrading human hemoglobin as a source of amino acids for their growth and maturation. Hemoglobin degradation is initiated by aspartic proteases, termed plasmepsins, with a cleavage at(More)
The facultative intracellular oyster parasite, Perkinsus marinus, taxonomically related to both dinoflagellates and apicomplexans, possesses at least two distinct genes (PmSOD1 and PmSOD2) predicted to encode iron-containing superoxide dismutases (FeSOD). DNA blots and sequence analysis suggest that both PmSOD1 and PmSOD2 are single copy and are unlinked.(More)
Plasmepsin II is one of the four catalytically active plasmepsins found in the food vacuole of Plasmodium falciparum. These enzymes initiate hemoglobin degradation by cleavage at the alpha-chain between Phe33 and Leu34. The crystal structures of Ser205 mutant plasmepsin II from P. falciparum in complex with two inhibitors have been refined at a resolution(More)
Cathepsin D (EC 3.4.23.5) is a lysosomal protease suspected to play important roles in protein catabolism, antigen processing, degenerative diseases, and breast cancer progression. Determination of the crystal structures of cathepsin D and a complex with pepstatin at 2.5 A resolution provides insights into inhibitor binding and lysosomal targeting for this(More)
The structure of the HIV-1 protease in complex with a pseudo-C2 symmetric inhibitor, which contains a central difluoroketone motif, has been determined with X-ray diffraction data extending to 1.7 A resolution. The electron density map clearly indicates that the inhibitor is bound in a symmetric fashion as the hydrated, or gemdiol, form of the(More)
The crystal structure of beef liver catalase [Murthy, Reid, Sicignano, Tanaka & Rossmann (1981). J. Mol. Biol. 152, 465-499] has now been refined by a restrained parameter least-squares method [Konnert & Hendrickson (1980). Acta Cryst. A36, 344-350] with respect to 2.5 A data. Some extra density was discovered during the refinement process. This was(More)
Infectious bursal disease is a highly contagious disease of young chickens caused by Infectious bursal disease virus (IBDV). Genome segment A encodes the capsid protein (VP2), while segment B encodes the RNA-dependent RNA polymerase (VP1). In the present study, we trace the molecular epidemiology of IBDV in Brazil by analyzing 29 isolates collected in the(More)