With purified DsRed1, we measured an extinction coefficient of 52,000 and a quantum yield of ∼0.7. Baird et al. (2000) reported a similar quantum yield but a higher extinction coefficient of 75,000; the reason for this discrepancy is unclear.
To overcome the slow maturation of DsRed, we used random and directed mutagenesis to create variants that mature 10–15 times faster than the wild-type protein. An asparagine-to-glutamine substitution at position 42 greatly accelerates the maturation of DsRed, but also increases the level of green emission. Additional amino acid substitutions suppress this green emission while further accelerating the maturation.