Abstract: A recombinant protein having luciferase activity and at least 60% similarity to a wild-type luciferase wherein in the sequence of the enzyme, the amino acid residue corresponding to residue 357 in Photinus pyralis luciferase is mutated as compared to the corresponding wild-type luciferase, such that the luciferase enzyme is able to emit light at a different wavelength as compared to the corresponding wild-type luciferase and/or has enhanced thermostability as compared to the corresponding wild-type luciferase. In general, the residue corresponding to 357 in Photinus pyralis luciferase is changed from an acidic amino acid to a non-acidic amino acid, and preferably an uncharged polar amino acid such as tyrosine. Mutant luciferases in accordance with the invention can produce a large (50 nm) wavelength shift in emitted light and have good thermostability. The resultant colour shift can be reversed by addition of coenzyme A. These properties make the mutant particularly useful in a variety of assays.

Abstract: A recombinant protein having luciferase activity and at least 60% similarity to a wild-type luciferase wherein in the sequence of the enzyme, the amino acid residue corresponding to residue 357 in Photinus pyralis luciferase is mutated as compared to the corresponding wild-type luciferase, such that the luciferase enzyme is able to emit light at a different wavelength as compared to the corresponding wild-type luciferase and/or has enhanced thermostability as compared to the corresponding wild-type luciferase. In general, the residue corresponding to 357 in Photinus pyralis luciferase is changed from an acidic amino acid to a non-acidic amino acid and preferably an uncharged polar amino acid such as tyrosine. Mutant luciferases in accordance with the invention can produce a large (50 nm) wavelength shift in emitted light and have good thermostability. The resultant colour shift can be reversed by addition of coenzyme A. These properties make the mutant particularly useful in a variety of assays.

Abstract: A method for detecting the presence of a lysed eukaryotic cell in a sample, said method comprising: (i) adding adenosine diphosphate (ADP) to said sample under conditions which allows the conversion of ADP to adenosine triphosphate (ATP) by cellular adenylate kinase, (ii) detecting ATP in said sample and relating that to the presence of adenylate kinase and thus to the presence of lysed cells. The method is useful in detecting the cell lysis, for example when screening for drugs which are required to cause lysis, for example for use in tumor therapy. However, in addition, cells may, in a preliminary step, be lysed and the contents quantitated in order to establish for example the health of condition of the cells or to detect the presence of cells in sample such as milk or urine, for diagnostic purposes.