Robertvk

A few lipases, such as Candida antarctica lipase A (CAL-A), are known to possess acyltransferase activity. This enables the enzyme to synthesize fatty acid esters from natural oils and alcohols even in the presence of bulk water. Unfortunately, fatty acids are still formed in these reactions as undesired side-products. To reduce the amount of fatty acids, several CAL-A variants were rationally designed based on its crystal structure. These variants were expressed in Escherichia coli and Pichia pastoris, purified, and their acyltransferase/hydrolase activities were investigated by various biocatalytic approaches. Among the investigated variants, mutant Asp122Leu showed a significant decrease in the hydrolytic activity, thus reducing the side-product yield during acylation. As desired, this variant retained wild-type process-relevant features like pH profile and thermostability.

Acyltransferase activity of CAL-A: Analysis of the CAL-A structure suggested 28 single-mutant variants to favor the desired acyltransferase activity. After screening, variant Asp122Leu exhibited significantly reduced production of free fatty acids, whereas the catalytic properties (e.g., thermostability, pH optimum) were not significantly altered.

All four stereoisomers of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) were synthesized in concise fashion using stereodivergent dual catalysis. Thus, following identical synthetic sequences and applying identical reaction conditions to the same set of starting materials, selective access to the four stereoisomers of THC was achieved in five steps.

No stereoisomer left behind: A concise synthesis of tetrahydrocannabinol (THC) is described that provides rapid and controlled access to any stereoisomer of the product, including the naturally occurring stereoisomers Δ⁹-trans-THC and Δ⁹-cis-THC. By application of stereodivergent dual catalysis to the same set of starting materials, all four isomers of THC were obtained in five steps using a uniform synthetic sequence and identical reaction conditions.