Marco Moracci

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Enzymes from hyperthermophilic organisms must operate at temperatures which rapidly denature proteins from mesophiles. The structural basis of this thermostability is still poorly understood. Towards a further understanding of hyperthermostability, we have determined the crystal structure of the beta-glycosidase (clan GH-1A, family 1) from the(More)
Hydrophobic residues in the core of a truncated form of chymotrypsin inhibitor 2 (CI2) have been mutated in order to measure their contribution to the stability of the protein. The free energy of unfolding of wild-type and mutants was measured by both guanidinium chloride-induced denaturation and differential scanning calorimetry. The two methods give(More)
Starch is, after cellulose, one of the most abundant polysaccharides produced by plants and is composed of amylose (15%–25%) and amylopectin (75%–85%). Amylose is a linear molecule consisting of 1,4-linked α-d-glucopyranose residues. Amylopectin is a branched polymer and contains α-1,6 glycosidic linkages in addition to the α-1,4 bonds. The hydrolysis of(More)
The enzyme with beta-galactosidase activity from Sulfolobus solfataricus strain MT-4, like other enzymes of this type isolated from thermophilic sources, has broad specificity for beta-D-gluco-, fuco- and galacto-sides. The beta-galactosidase activity was purified by a new procedure that improved yields (44%) and final specific activity (182 units mg-1 at(More)
Aphidius ervi is an endophagous braconid, parasitoid of the pea aphid, Acyrthosiphon pisum. A. ervi teratocytes, deriving from the dissociation of the embryonic serosa, synthesize and release two major proteins into the host haemocoel. The gene of one of these proteins has been cloned and characterized. This gene codes for a 15.8 kDa protein belonging to(More)
Transition-state mimicry is increasingly important both to understand enzyme mechanism and to direct the synthesis of putative therapeutic agents. X-ray crystallography is able to provide vital information on the interactions between an enzyme and the potential inhibitor. Here we report the structures, at approximately 2 A resolution, of a family GH1(More)
The beta-glycosidase from the hyperthermophilic Archaeon Sulfolobus solfataricus hydrolyzes beta-glycosides following a retaining mechanism based upon the action of two amino acids: Glu387, which acts as the nucleophile of the reaction, and Glu206, which acts as the general acid/base catalyst. The activities of inactive mutants of the catalytic nucleophile(More)
We here report the first molecular characterization of an alpha-xylosidase (XylS) from an Archaeon. Sulfolobus solfataricus is able to grow at temperatures higher than 80 degrees C on several carbohydrates at acidic pH. The isolated xylS gene encodes a monomeric enzyme homologous to alpha-glucosidases, alpha-xylosidases, glucoamylases and(More)
The Sulfolobus solfataricus, strain MT4, beta-glycosidase (Ss beta-gly) is a thermophilic member of glycohydrolase family 1. To identify active-site residues, glutamic acids 206 and 387 have been changed to isosteric glutamine by site-directed mutagenesis. Mutant proteins have been purified to homogeneity using the Schistosoma japonicum glutathione(More)