Structure-guided protein engineering of ammonia lyase for efficient synthesis of sterically bulky unnatural amino acids

Bioresources and Bioprocessing

Table 2 Properties of the EcMAL variants

Enzyme and mutants	Mutation sites	Specific activity (U/g_protein)^a	% ee^b
WT EcMAL	None	nd^c	nd^c
M1	Q329S/K331R	5.4 ± 0.5	16 (S)
M2	Q73F/Y240C	4.4 ± 0.4	4.4 (S)
M3	F170L/E172F	2.5 ± 0.5	39 (S)
M4	Q329S/K331G/C361C	6.2 ± 0.8	86(S)
M5	Q73V/Y240C/D277C	7.3 ± 0.1	28(S)
M6	F170S/E172R/D307L	9.0 ± 0.3	79 (S)
M7	Q329F/K331R/Y356S/C361L	26.2 ± 0.2	99 (S)
M8	E172R/Y240S/D307L/Q329F/Y356S/C361L	38.6 ± 0.5	99 (S)

^aSpecific activity was determined at pH 8.0 and 30 °C using purified enzyme and omeprazole sulfide
^bThe ee values were determined by HPLC
^cNot detected
^dThe bold mutations indicate newly involved mutation(s) in each round