1. MicroSpectroscopy Centre, Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA, Wageningen, The Netherlands, Laboratory of Molecular Recognition and Antibody Technology, Wageningen University, Binnenhaven 10, 6709 PD Wageningen, The Netherlands, and Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands