'Organic phase buffers' control biocatalyst activity independent of initial aqueous pH

Combinations of triisooctylamine with its hydrochloride, or of triphenylacetic acid with its Na+ salt, can function as buffers for use during biocatalysis in organic media. They can control the pH of an adjacent aqueous phase, even though both forms of each buffer remain in the organic phase. With 0.1 M aqueous NaCl, the mid-point pH values obtained with the two buffer systems are around pH 4.5 and 7.0, respectively. The activity of an immobilized subtilisin Carlsberg shows a strong dependence on the ratio of the two forms of the triphenylacetic acid buffer system. Without the buffer, the rate shows the normal dependence on the pH of the aqueous solution before drying; however, this is almost eliminated if the buffer is used. The amine buffer system can similarly affect the activity of an immobilized Rhizomucor miehei lipase.