Patent ID: 7052863

Claim:
A method for detecting enzyme activity comprising bringing at least one substrate, the target part of which matches the activity of the enzyme being assayed, into contact with a sample suspected of containing at least one microorganism which expresses said enzyme activity, and at least one type of cation, and monitoring for the formation of an insoluble, colored chelation complex, wherein said substrate has following general formula: in which: R 1 is a target part or H, and R 2 is a target part or H, with at least one of R 1 and R 2 being a target part, R 3 is H, SO 3 H, Cl, Br, F, I, NO 2 , NH 2 , NR 9 R 10 , or an acylamino, aminoaryl, or aminoacylamino group of the type NHCOX, with X being an alkyl, aryl or aralkyl group or an a-amino acid residue, R 4 is H, SO 3 H, Cl, Br, F, I, NO 2 , NH 2 , NR 9 R 10 , OH or an acylamino aminoaryl or aminoacylamino group of the type NHCOX, with X being an alkyl, aryl or aralkyl group or an a-amino acid residue, alternatively, R 3 and R 4 form bonds with one another to create a ring with at least five sides, R 5 , R 6 , R 7 and R 8 are each independently selected from the group consisting of H, a halogen, OH, SO 3 H, an alkyl group and an alkoxy group, and R 9 and R 10 are independently an alkyl, aryl, aralkyl group, or either R 9 or R 10 is a ring structure with the other, either R 10 or R 9 , being a hydrogen atom.