Patent ID: 8071761

Claim:
A method of preparing a fluorescent substrate for Î²-lactamase, said method comprising: providing a first fluorescent molecule having a first-reactive functional group, a second fluorescent molecule having a second-reactive functional group and a cephalosporin compound having the formula: wherein G is selected from the group consisting of SH, NH 2 , OH and a bifunctional aliphatic acid moiety; Q is selected from the group consisting of halogen, acetate, and thiol; and R 0 is selected from the group consisting of H, and a moiety that forms an ester with the CO 2 moiety drawn in the formula; and contacting the cephalosporin compound with the first fluorescent molecule and the second fluorescent molecule, wherein the first-reactive functional group reacts with G and the second-reactive functional group reacts with Q to form the fluorescent substrate, wherein the first fluorescent molecule and the second fluorescent molecule are capable of operating by fluorescence resonance energy transfer.