1. Proteomics Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Dr. Aiguader 80, 08003 Barcelona, Spain, Instituto Universitario de Química Organometálica “Enrique Moles”, Universidad de Oviedo, 33071 Oviedo, Spain, Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain, and Unit for Glycoconjugate Chemistry, IIQAB-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain