Industrial Biotransformations

Catalase
Microbial source
1) Reaction conditions
pH: 6.0–9.0
medium: 3-phase-system: organic, solid, aqueous
reaction type: redox reaction
catalyst: solubilized
enzyme: hydrogen-peroxide: hydrogen peroxide oxidoreductase (catalase)
strain: microbial source
CAS (enzyme): [9001-05–2]
2) Remarks
O2 + 2
1
Me
NO 2
EC 1.11.1.6
● During oxidative coupling to dinitrodibenzyl (DNDB) hydrogen peroxide is produced as a byproduct.
It is not possible to decompose H 2O 2 by the addition of heavy-metal catalysts because
only incomplete conversion is reached. Additionally, subsequent process steps with DNDB are
problematic due to contamination with heavy-metal catalyst.
● The reaction solution consists of three phases: 1) water, 2) organic phase and 3) solid phase
consisting of DNDB.
● The catalase derived from microbial source has advantages compared to beef catalase since the
activity remains constant over a broad pH range from 6.0 to 9.0; temperatures up to 50 °C are
tolerated and salt concentrations up to 25 % do not affect the enzyme stability.
● The reaction is carried out in a cascade of CSTRs. After the chemical reaction in the first vessel,
the pH is adjusted with acetic acid. Decomposition of H 2O 2 is induced by catalase solution
added to the second reactor at a constant rate. Oxygen is removed by dilution with nitrogen in
the third reactor.
O 2N
NO2
2
H2O2
H2O + 1/2 O2
1 = nitrotoluene
2 = dinitrodibenzyl (DNDB) Novartis
Fig. 1.11.1.6 – 1
(t-BuOK)
+
E
217