Construction of an in vitro bypassed pyruvate decarboxylation pathway using thermostable enzyme modules and its application to N-acetylglutamate production

Table 1 pH profile of enzyme activity

Buffer	pH	Specific activity (U mg^-1total protein)^a				Total protein concentration (mg ml^-1)^b
Buffer	pH	Ap PDC	Tt ADDH	Tt GDH	Tm NAGS
MES	6.0	0.046	0.067	0.164	0.154	1.97
MES	6.5	0.066	0.146	0.255	0.169	1.27
HEPES	7.0	0.078	0.137	0.291	0.208	1.13
HEPES	7.5	0.058	0.197	0.184	0.215	1.30
Bicine	8.0	0.046	0.246	0.074	0.220	1.75
Bicine	8.5	0.025	0.450	0.026	0.227	3.37

^aSpecific activities are expressed as those from the crude extract of recombinant E. coli before the heat treatment.
^bTotal protein concentrations in the mixture of crude extracts containing 0.04 U of each of the enzyme are calculated.

ISSN: 1475-2859