title: Ultrasonic energy as a new tool for fast isotopic 18O labeling of proteins for mass spectrometry-based techniques: preliminary results.
abstract: Preliminary results regarding fast isotopic labeling of proteins with (18)O in conjunction with matrix assisted laser desorption ionization time of flight mass spectrometry technique are presented. Similar (16)O/(18)O isotopic labeling ratios were found for the overnight procedure (12h) and the new fast ultrasonic one (30 min) for the BSA, ovalbumin and alpha-lactalbumin proteins. The procedure, however, failed to promote double (18)O isotopic labeling for the proteins, ovalbumin and alpha-lactalbumin. Two different sonication frequencies, 35 and 130 kHz, were studied at two different sonication times of 15 and 30 min, being best results obtained with the procedure at 130 kHz of sonication frequency and 30 min of sonication time. For comparative purposes the overnight isotopic (18)O labeling procedure was done. In addition, the new fast isotopic labeling procedure was also studied without ultrasonication, in a water bath at 60 degrees C.
authors.affiliation: REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Monte de Caparica, Portugal.
authors.forename: R J
authors.initials: RJ
authors.lastname: Carreira
authors.forename: R
authors.initials: R
authors.lastname: Rial-Otero
authors.forename: D
authors.initials: D
authors.lastname: López-Ferrer
authors.forename: C
authors.initials: C
authors.lastname: Lodeiro
authors.forename: J L
authors.initials: JL
authors.lastname: Capelo
mesh_terms: D000818:Animals; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D007768:Lactalbumin; D013058:Mass Spectrometry / Q000379:methods*; D010047:Ovalbumin; D010103:Oxygen Isotopes / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D012710:Serum Albumin, Bovine; D014465:Ultrasonics
chemical_list: D010103:Oxygen Isotopes; D011506:Proteins; D012710:Serum Albumin, Bovine; D010047:Ovalbumin; D007768:Lactalbumin