title: Non-thermal effects of microwaves on proteins: thermophilic enzymes as model system.
abstract: Two thermophilic and thermostable enzymes, isolated from Sulfolobus solfataricus, S-adenosylhomocysteine hydrolase and 5'-methylthioadenosine phosphorylase, were exposed to 10.4 GHz microwave radiation in order to discriminate between thermal and non-thermal microwave effects. The exposure causes a non-thermal, irreversible and time-dependent inactivation of both enzymes; the inactivation rate is related to the energy absorbed and is independent of the enzyme concentration. The influence of salts on enzyme inactivation has also been investigated. Conformational changes of S-adenosylhomocysteine hydrolase, detected by fluorescence and circular dichroism techniques, suggest that microwaves induce protein structural rearrangements not related to temperature.
authors.affiliation: Facoltà di Medicina e Chirurgia, Seconda Universita di Napoli, Naples,Italy.
authors.forename: M
authors.initials: M
authors.lastname: Porcelli
authors.forename: G
authors.initials: G
authors.lastname: Cacciapuoti
authors.forename: S
authors.initials: S
authors.lastname: Fusco
authors.forename: R
authors.initials: R
authors.lastname: Massa
authors.forename: G
authors.initials: G
authors.lastname: d'Ambrosio
authors.forename: C
authors.initials: C
authors.lastname: Bertoldo
authors.forename: M
authors.initials: M
authors.lastname: De Rosa
authors.forename: V
authors.initials: V
authors.lastname: Zappia
mesh_terms: D043383:Adenosylhomocysteinase; D002942:Circular Dichroism; D004795:Enzyme Stability; D006358:Hot Temperature; D006867:Hydrolases / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D007700:Kinetics; D008872:Microwaves; D011487:Protein Conformation / Q000528:radiation effects; D011683:Purine-Nucleoside Phosphorylase / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D013050:Spectrometry, Fluorescence; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase; D006867:Hydrolases; D043383:Adenosylhomocysteinase