Industrial Biotransformations

2.2 Enzyme Classes
A further addition of water to the product could lead to an oxo acid. This is the case for
some amino acids, where ammonia is then eliminated.
EC 4.3 Carbon–nitrogen lyases
R 1
R 2N
R 2
H
R4
3
R
NR 2
R = organic residue
or
R 1
R 2
R 4
R 3
+ HNR 2
R 2 R 1 OH + HNR2 R 1
R 2
O
The resulting double bond can change its position in order to deliver a more stable product,
for instance in the case of keto–enol tautomerism. The product can also undergo a
further reaction.
EC 4.4 Carbon–sulfur lyases
R 1
S
R 2
H
R4
3
R
S = SH, (di)substituted sulfide, sulfur-oxide, SeH
R = organic residue
R 1
R 2
R 4
R 3
+ S H
According to Enzyme Nomenclature the carbon–selenium lyase also belongs to this subclass.
Similarly to other lyases, further reactions can occur on the product. In the case of
disubstituted sulfides, there is no hydrogen bonded to the sulfur in the product.
EC 4.5 Carbon–halide lyases
R 1
X
R 2
H
R4
3
R
X = halogen
R = organic residue
R 1
R 2
R 4
R 3
+ HX
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