Table 3.

Characteristics of improved FbFP F37S and F37T mutants

Property	FbFP	FbFP F37S	FbFP F37T
Oligomeric state	1.81 (dimer)	1.78 (dimer)	1.87 (dimer)
Quantum yield	0.17 [21]	0.30 ± 0.01	0.24 ± 0.01
Fraction of holoprotein	0.33 ± 0.01	0.49 ± 0.01	0.45 ± 0.03

Enhanced brightness F37S and F37T mutants were characterized with respect to their oligomeric state, holoprotein fraction, and quantum yield in order to elucidate a biochemical and biophysical basis for the origin of improved fluorescence in these mutants. Specifically, we identified higher quantum yield and improved association with FMN in the mutant proteins as key contributors to their brighter fluorescence emission. Standard errors were calculated from at least four replicate measurements.