SUPPORTING INFORMATION Unusual Chromophore and Crosslinks in Ranasmurfin- a Blue Protein from the Foam Nests of a Tropical Frog

Author contributions: AC and MWK devised and initiated the project and, together with RTYC, undertook fieldwork, sample collection and initial protein characterization. RTYC did the sample purification, analysis and de novo sequencing together with CB (Glasgow) and CHB (St. Andrews). AAL provided laboratory facilities and assisted with fieldwork arrangements in Malaysia. Protein crystallography was done by MO, MFW, LGC, KAJ, HL, SAM, MAW and JHN. AC & JHN did the chemistry. AC, JHN and MO wrote the manuscript, in consultation with other authors. Etymology: The name "ranasmurfin " derives from the latin rana (frog) and the popular blue cartoon characters (the Smurfs). The specific shorthand designation, Pl-RSF-1, comes from Polypedates leucomystax ranasmurfin; this being the 1st example of a potentially larger family of similar proteins