Sandro Roberto Marana

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Two beta-glycosidases (BG) (Mr 47,000 and Mr 50,000) were purified from Spodoptera frugiperda (Lepidoptera: Noctuidae) midguts. These two polypeptides associate or dissociate depending on the medium ionic strength. The Mr 47,000 BG probably has two active sites. One of the putative active sites (cellobiase site) hydrolyses p-nitrophenyl beta-D-glucoside(More)
A beta-glycosidase (M(r) 50000) from Spodoptera frugiperda larval midgut was purified, cloned and sequenced. It is active on aryl and alkyl beta-glucosides and cellodextrins that are all hydrolyzed at the same active site, as inferred from experiments of competition between substrates. Enzyme activity is dependent on two ionizable groups (pK(a1)=4.9 and(More)
Trypsins have high sequence similarity, although the responses of insect trypsins to chemical and natural inhibitors suggest they differ in specificities. Purified digestive trypsins from insects of four different orders were assayed with internally quenched fluorescent oligopeptides with two different amino acids at P1 (Arg/Lys) and 15 amino acid(More)
Enhanced mitochondrial generation of oxidants, including hydrogen peroxide (H2O2), is related to a large number of pathological conditions, including diet-induced obesity and steatohepatosis. Indeed, we have previously shown that high fat diets increase the generation of H2O2 in liver mitochondria energized by activated fatty acids. Here, we further study(More)
ss-glycosidases are active upon a large range of substrates. Besides this, subtle changes in the substrate structure may result in large modifications on the ss-glycosidase activity. The characterization of the molecular basis of ss-glycosidases substrate preference may contribute to the comprehension of the enzymatic specificity, a fundamental property of(More)
Two beta-glycosidases (M(r) 59k) were purified from midgut contents of larvae of the yellow mealworm, Tenebrio molitor (Coleoptera: Tenebrionidae). The two enzymes (betaGly1 and betaGly2) have identical kinetic properties, but differ in hydrophobicity. The two glycosidases were cloned and their sequences differ by only four amino acids. The T. molitor(More)
The design of beta-glycosidases with planed substrate specificity for biotechnological application has received little attention. This is mostly a consequence of the lack of data on the molecular basis of the beta-glycosidase specificity, namely data on the energy of the noncovalent interactions in the enzyme-transition state complex. In an attempt to fill(More)
The specificity of the Spodoptera frugiperda digestive beta-glycosidase (Sfbetagly50) for fucosides, glucosides and galactosides is determined by noncovalent interactions of glycone 6-OH and glycone 4-OH with the active-site residues Q39 and E451. Site-directed mutagenesis and enzyme steady-state kinetics were described, showing that replacement of E451(More)
Lysozymes from family 22 of glycoside hydrolases are usually part of the defense system against bacteria. However in ruminant artiodactyls and saprophagous insects, lysozymes are involved in the digestion of bacteria. Here, we report the first crystallographic structure of a digestive lysozyme in its native and complexed forms, the structure of lysozyme 1(More)
Enzymes enhance chemical reaction rates by lowering the activation energy, the energy barrier of the reaction leading to products. This occurs because enzymes bind the high-energy intermediate of the reaction (the transition state) more strongly than the substrate. We studied details of this process by determining the substrate binding energy (DeltaG(s),(More)