Ultramarine, a chromoprotein acceptor for förster resonance energy transfer

Abstract

We have engineered a monomeric blue non-fluorescent chromoprotein called Ultramarine (fluorescence quantum yield, 0.001; ε 585nm, 64,000 M-1. cm-1) for use as a Förster resonance energy transfer acceptor for a number of different donor fluorescent proteins. We show its use for monitoring activation of caspase 3 in live cells using fluorescence lifetime imaging. Ultramarine has the potential to increase the number of cellular parameters that can be imaged simultaneously. © 2012 Pettikiriarachchi et al.