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Continuous enzymatic transformation in an enzyme membrane reactor with simultaneous NAD(H) regeneration
Author(s) -
Wichmann Rolf,
Wandrey Christian,
Bückmann Andreas F.,
Kula MariaRegina
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(20000320)67:6<791::aid-bit15>3.0.co;2-i
Subject(s) - formate dehydrogenase , nad+ kinase , cofactor , chemistry , biochemistry , enzyme , dehydrogenase , formate , polyethylene glycol , chromatography , membrane , catalysis
Multienzyme reaction systems with simultaneous coenzyme regeneration have been investigated in a continuously operated membrane reactor at bench scale. NAD(H) covalently bound to polyethylene glycol with a molecular weight of 10 4 [PEG‐10,000‐NAD(H)] was used as coenzyme. It could be retained in the membrane reactor together with the enzymes. L ‐leucine dehydrogenase (LEUDH) was used as catalyst for the reductive amination of α‐ketoisocaproate (2‐oxo‐4‐methylpentanoic acid) to L ‐leucine. Formate dehydrogenase (FDH) was used for the regeneration of NADH. Kinetic experiments were carried out to obtain data which could be used in a kinetic model in order to predict the performance of an enzyme membrane reactor for the continuous production of L ‐leucine. The kinetic constants V max and k m of the enzymes are all in the same range regardless of whether native NAD(H) or PEG‐10,000‐NAD(H) is used as coenzyme. L ‐leucine was produced continuously out of α‐ketoisocaproate for 48 days; a maximal conversion of 99.7% was reached. The space–time yield was 324 mmol/L day (or 42.5 g/L day).