Engineered imine reductases and methods for the reductive amination of ketone and amine compounds

A process for preparing an amine compound of formula (III),

• wherein
• R1 and R2 groups are independently selected from a hydrogen atom, and optionally substituted alkyl, alkenyl, alkynyl, alkoxy, carboxy, aminocarbonyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carboxyalkyl, aminoalkyl, haloalkyl, alkylthioalkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, heteroaryl, and heteroarylalkyl;
• and optionally R1 and R2 are linked to form a 3-membered to 10-membered ring;
• R3 and R4 groups are independently selected from a hydrogen atom, and optionally substituted alkyl, alkenyl, alkynyl, alkoxy, carboxy, aminocarbonyl, heteroalkyl, heteroalkenyl, heteroalkynyl, carboxyalkyl, aminoalkyl, haloalkyl, alkylthioalkyl, cycloalkyl, aryl, arylalkyl, heterocycloalkyl, heteroaryl, and heteroarylalkyl, with the proviso that both R3 and R4 cannot be hydrogen;
• and optionally R3 and R4 are linked to form a 3-membered to 10-membered ring;
• and
• optionally, the carbon atom and/or the nitrogen indicated by * is chiral;
• the process comprising contacting
• a compound of formula (I),
• wherein
• R1, and R2 are as defined above;
• and
• a compound of formula (II),
• wherein
• R3, and R4 are as defined above;
• with an engineered polypeptide, wherein the engineered polypeptide has imine reductase activity in presence of a cofactor under suitable reaction conditions and wherein the engineered polypeptide comprises an amino acid sequence with at least 90 sequence identity to a reference sequence of SEQ ID NO:6 and a residue difference at position 82, as compared to SEQ ID NO:6.