| TECHNOLOGY |
"We've developed a two-phase system where a chemical reaction to be screened takes place in an organic layer, leading to a product that can diffuse into an aqueous layer, where an enzymatic system detects it and reports back on the relative rate," Berkowitz explains. A big advantage, he notes, is that the reporting takes place immediately, while the reaction is occurring. A second advantage is that the chemists don't have to attach a chromophore or a fluorescent probe to their reaction substrate. Such probes can change reaction rates, thereby creating a mistaken impression of the effectiveness of the catalyst. Leaving them off also simplifies the chemistry. IN PARALLEL Nickel-catalyzed allylic amination reaction taking place in organic layer produces ethanol as a by-product, which, being polar, diffuses into the aqueous layer where it serves as substrate for the enzyme alcohol dehydrogenase (ADH). A second enzyme, aldehyde dehydrogenase (AIDH), further oxidizes the reaction product to acetic acid. Each enzymatic reaction also produces a molecule of the reduced form of nicotinamide adenine dinucleotide (NADH). This production is monitored spectrophotometrically in real time.
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