Asymmetric β‐Methylation of l ‐ and d ‐α‐Amino Acids by a Self‐Contained Enzyme Cascade

This report describes a modular enzyme‐catalyzed cascade reaction that transforms l ‐ or d ‐α‐amino acids to β‐methyl‐α‐amino acids. In this process an α‐amino acid transaminase, an α‐keto acid methyltransferase, and a halide methyltransferase cooperate in two orthogonal reaction cycles that mediate product formation and regeneration of the cofactor pyridoxal‐5′‐phosphate and the co‐substrate S‐adenosylmethionine. The only stoichiometric reagents consumed in this process are the unprotected l ‐ or d ‐α‐amino acid and methyl iodide.