DsRed(S197Y) is a red fluorescent protein with an excitation peak of 558nm and an emission peak of 585nm in vitro. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Discosoma drFP583 gene (GenBank:AF168419; AAF03369), containing the mutation S197Y. DsRed(S197Y) is brighter than drFP583 and essentially lacks the secondary emission peak seen at around 500nm when drFP583 is excited within the 440-490nm range (FBrf0137270).