On the inactivity of Candida antartica lipase B towards strong acids

Candida antarctica lipase B (CalB, Novozyme 435) was evaluated as catalyst for the conversion of so-called edible acids (e.g. malic and tartaric acid). While transesterification using these acyl donors proceeds smoothly, albeit with low regioselectivity, esterification is hardly catalyzed.As major reason for CalB inactivation the high acidity of edible acids was identified leading to irreversible inactivation of the biocatalyst. Furthermore, indication exist that all acids exhibiting a pKa value below 4.8 cause irreversible inactivation of CalB.

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