Conformational stability of ageritin, a metal binding ribotoxin-like protein of fungal origin(57 views) Lampitella E, Landi N, Oliva R, Ragucci S, Petraccone L, Berisio R, Di Maro A, Del Vecchio P
Keywords: Differential Scanning Calorimetry, Protein Thermodynamic Stability, Spectroscopy,
Affiliations: *** IBB - CNR ***
Department of Chemical Sciences, University of Naples Federico II, Via Cintia, I-80126 Napoli, Italy.
Department of Environmental, Biological and Pharmaceutical Sciences and Technologies (DiSTABiF), University of Campania Luigi Vanvitelli, Via Vivaldi 43, I-81100 Caserta, Italy.
Istituto di Biostrutture e Bioimmagini, C.N.R., Via Mezzocannone 16, I-80134 Napoli, Italy.
References: Not available.
Conformational stability of ageritin, a metal binding ribotoxin-like protein of fungal origin
Ageritin is a ribotoxin-like protein of biotechnological interest, belonging to a family of ribonucleases from edible mushrooms. Its enzymatic activity is explicated through the hydrolysis of a single phosphodiester bond, located in the sarcin/ricin loop of ribosomes. Unlike other ribotoxins, ageritin activity requires divalent cations (Zn(2+)). Here we investigated the conformational stability of ageritin in the pH range 4.0-7.4, using calorimetric and spectroscopic techniques. We observed a high protein thermal stability at all pHs with a denaturation temperature of 78 °C. At pH 5.0 we calculated a value of 36 kJ mol(-1) for the unfolding Gibbs energy at 25 °C. We also analysed the thermodynamic and catalytic behaviour of S-pyridylethylated form, obtained by alkylating the single Cys18 residue, which is predicted to bind Zn(2+). We show that this form possesses the same activity and structure of ageritin, but lower stability. In fact, the corresponding values of 52 °C and 14 kJ mol(-1) were found. Conservation of activity is consistent with the location of alkylation site on the opposite site of the catalytic site cleft. Inasmuch as Cys18 is part of a structurally stabilizing zinc-binding site, disrupted by cysteine alkylation, our results point to an important role of metal ions in ageritin stability.
Conformational stability of ageritin, a metal binding ribotoxin-like protein of fungal origin
Kállay C, Dávid A, Timári S, Nagy EM, Sanna D, Garribba E, Micera G, De Bona P, Pappalardo G, Rizzarelli E, Sóvágó I * Copper(II) complexes of rat amylin fragments(517 views) Dalton T (ISSN: 1477-9234, 1477-9226, 1477-9234electronic), 2011 Oct 14; 40(38): 9711-9721. Impact Factor:3.838 ViewExport to BibTeXExport to EndNote