A red-fluorescent substrate microarray for lipase fingerprinting

A lipase substrate microarray was obtained by printing aliphatic C2-C12 monoesters of (5R)- and (5S)-3-(5,6-dihydroxyhexyloxy)benzaldehyde by reductive alkylation on amine-functionalized glass slides coated with bovine serum albumin and a short PEG linker. The microarray features 12 substrates and their 66 possible binary mixtures spotted in a 9 x 36 spot array. Lipase reactions are detected by chemoselective NaIO4-oxidation of the 1,2-diol hydrolysis product to form an aldehyde, which is then tagged with the red-fluorescent dye rhodamine B sulfohydrazide 1. Specific fingerprints are produced by active enzymes. These experiments provide the first example of lipase fingerprinting using microarrays.