A new bifunctional fluorescent label, BRos, was synthesised in order to monitor protein dynamics using fluorescence microscopy, and the photophysical properties were compared with those of bifunctionalised rhodamine, BRho. In a labelling experiment with a model peptide of troponin C, which regulates muscle contraction and relaxation, it was found that BRos was bound to the peptide through two linkages and provided a homogeneous ...