Effects of 2.45 GHz microwave fields on liposomes entrapping glycoenzyme ascorbate oxidase: evidence for oligosaccharide side chain involvement.
Previous observations reported by our group indicate that 2.45 GHz microwave fields at specific absorption rate (SAR) of 5.6 W/kg reduce the enzyme activity rate of ascorbate oxidase (AO) trapped in liposomes. In this study, we report dose-response studies on these AO containing liposomes irradiated at different SAR values (1.4, 2.8, 4.2, and 5.6 W/kg). No response was observed for SAR below 5.6 W/kg. Liposomes entrapping functional AO in its deglycated form (AO-D) were also used. In this case, no MW related enzyme activity changes were observed, demonstrating a direct involvement of oligosaccharide chains of AO. Furthermore, the catalytic properties of both AO and AO-D were not impaired by MW irradiation, neither in homogeneous solution nor loaded in liposomes, excluding possible changes in the conformation of enzyme as a mechanism. Our results suggest that the oligosaccharide chains of AO are critical to elicit the microwave observed effects on lipid membrane.
Ramundo-Orlando
Alfonsina
A
ICEmB at Institute of Neurobiology and Molecular Medicine-CNR, Roma, Italy.
Liberti
Micaela
M
Mossa
Giuseppe
G
D'Inzeo
Guglielmo
G
D001204:Ascorbate Oxidase / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D001205:Ascorbic Acid / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007700:Kinetics; D008081:Liposomes / Q000528:radiation effects; D008872:Microwaves; D009844:Oligosaccharides / Q000737:chemistry / Q000528:radiation effects*; D010084:Oxidation-Reduction; D011487:Protein Conformation / Q000528:radiation effects
D008081:Liposomes; D009844:Oligosaccharides; D001204:Ascorbate Oxidase; D001205:Ascorbic Acid