n-Hexane can be isolated from natural gas and
crude oil. It is used in food processing, including the extraction of vegetable
oils, and as a solvent in various products and processes. In the atmosphere, the
half-life of n-Hexane is estimated to be less than 2 days.
The available data suggest that the acute toxicity of n-Hexane is low. Single
exposures to n-Hexane can cause vertigo, giddiness, and drowsiness. n-Hexane is
a mild skin irritant that causes transient erythema when in short-term contact
with skin; it can also irritate the eyes. Chronic high level n-Hexane exposure
damages the nervous system, initially producing a lack of feeling in the
extremities and possibly progressing to a more severe nerve damage.
The anaerobic biodegradation of n-Hexane starts by addition of fumate, similar to the anerobic toluene pathway. The pathway was proposed by Wilkes et al., 2002.
The following is a text-format n-Hexane pathway map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic format: nhex1 (15k) and nhex2 (14k).
n-Hexane
denitrifying bacterium
|
+--------->Fumarate---->| non-specific
| | (1-methylpentyl)-
| | succinate synthase
| |
| v
| (1-Methylpentyl)succinate
| |
| |
| | non-specific
| | CoA-transferase
| |
| v
| (1-Methylpentyl)succinyl-CoA
| |
| |
| | methylmalonyl-CoA
| | mutase
| |
| v
| (2-Methylhexyl)malonyl-CoA
| |
^ |
| | methylmalonyl-CoA
| | carboxyltransferase
| |
| v
| 4-Methyloctanoyl-CoA
| |
| | non-specific
| | 4-methyloctanoyl-CoA
| | dehydrogenase
| |
| v
| 4-Methyloct-2-enoyl-CoA
| |
| | non-specific
| | 4-methyloct-2-enoyl-CoA
| | hydratase
| |
| v
| 3-Hydroxy-4-methyloctanoyl-CoA
| |
| | non-specific
| | 3-hydroxy-4-methyloctanoyl-CoA
| | dehydrogenase
| |
| v
| 4-Methyl-3-oxooctanoyl-CoA
| |
| | non-specific
| | 2-methylhexanoyl-CoA
| | C-acetyltransferase
| |
| v
| 2-Methylhexanoyl-CoA + Acetyl-CoA ----> to Intermediary Metabolism (KEGG)
| |
| |
| | non-specific
| | 2-methylhexanoyl-CoA
| | dehydrogenase
| |
| v
| 2-Methylhex-2-enoyl-CoA
| |
| | non-specific
^ | 2-methylhex-2-enoyl-CoA
| | hydratase
| |
| v
| 3-Hydroxy-2-methylhexanoyl-CoA
| |
| | non-specific
| | 3-hydroxy-2-methylhexanoyl-CoA
| | dehydrogenase
| |
| v
| 2-Methyl-3-oxohexanoyl-CoA
| |
| | non-specific
| | butyryl-CoA
| | C-propionyltransferase
| |
| v
+----------Butyryl-CoA + Propanoyl-CoA
|
|
|
|
|
v
Intermediary
Metabolism
(KEGG)
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