# Cupin‐Type Dimethylsulfoniopropionate Lyase from Pelagibacter ubique (DddK Pu ) Catalyzes Aza‐Michael Addition of Primary and Secondary Amines to Acrylic Acid

## TL;DR

A protein from a marine bacterium efficiently catalyzes a key chemical reaction to make amino acids used in drug production.

## Contribution

A novel biocatalytic method using DddK Pu for aza-Michael addition to synthesize β-amino acids with high selectivity.

## Key findings

- DddK Pu catalyzed aza-Michael addition with 90%–100% conversion and 40%–86% yields for secondary amines.
- The W26G variant achieved 50%–100% conversion and 43%–81% yields for primary amines.
- The enzyme showed chemoselectivity for specific amine substrates.

## Abstract

The formation of carbon─nitrogen (C─N) bonds is a cornerstone of organic synthesis, underpinning the production of amines, imines, and nitriles found in numerous active ingredients. Among the methods for C─N bond formation, the aza‐Michael addition stands out as a powerful and versatile approach. Herein, we present a biocatalytic strategy for the efficient aza‐Michael addition of primary and secondary amines to acrylic acid, i.e., aza‐Michaelase activity, leveraging the promiscuity of dimethylsulfoniopropionate (DMSP) lyase from Pelagibacter ubique HTCC1062 (DddK
Pu
). In vivo DddK
Pu
catalyzes the β‐elimination of DMSP to sodium acrylate and dimethylsulfide (i.e., a retro sulfa‐Michael reaction). Here, we screened DddK
Pu
against a diverse library of 30 primary and 44 secondary amines. The wild‐type enzyme achieved 90%–100% conversion and 40%–86% isolated yields of N,N‐disubstituted‐β‐amino acids with secondary amines. For primary amines, the W26G variant proved optimal, furnishing 50%–100% conversion and 43%–81% isolated yields of N‐substituted‐β‐amino acids. Notably, the enzyme exhibited remarkable chemoselectivity: for pyrrolidin‐2‐ylmethanamine, the reaction occurred exclusively at the secondary amine, while for piperidin‐2‐ylmethanamine, it reacted selectively at the primary amine. These findings highlight DddK
Pu
as a versatile biocatalyst for the selective synthesis of β‐amino acids, expanding the toolbox for C─N bond formation.

A dimethylsulfoniopropionate lyase (DddK) was identified as an efficient aza‐Michaelase for the addition of amines to acrylate. Screening 74 amines with wild‐type DddK and its W26G variant yielded N‐substituted and N,N‐disubstituted β‐amino acids in 30%–93% isolated yield. This versatile method enables access to novel β‐amino acids, which serve as valuable building blocks for pharmaceutical synthesis.