This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Carbohydrates Biosynthesis → Alkanes Biosynthesis|
Organisms produce hydrocarbons of different types by different mechanisms. Several mechanisms have been described for the production of hydrocarbons from fatty acids or their intermediates, including synthesis of alkanes from fatty aldehydes by decarbonylation (see alkane biosynthesis I and alkane biosynthesis II), synthesis of long-chain olefins by head-to head condensation of fatty acids (see for example hentriaconta-3,6,9,12,15,19,22,25,28-nonaene biosynthesis), and production of alkenes from fatty acids by decarboxylation (see terminal olefins biosynthesis I and terminal olefins biosynthesis II).
Botryococcus braunii, a green colonial microalga, is regarded as a potential source of biofuel because of its ability to produce large amounts of hydrocarbons. Depending on the strain and growth conditions, up to 75% of algal dry mass can be hydrocarbons. Different strains of Botryococcus braunii produce different hydrocarbons. Three races have been documented: Botryococcus braunii BOT88-2 (A race) produces odd numbered (C25 to C31) n-alkadienes and trienes, Botryococcus braunii BOT22 (B race) produces triterpenoid hydrocarbons known as botryococcenes (CnH2n-10, n = 30-37) of isoprenoid origin [Chisti80], and the L race produces lycopadiene, a C40 tetraterpene [Metzger90].
About This Pathway
Alkanes are produced in multiple organisms - for example, in the production of plant cuticular waxes [Samuels08], as insect pheromones [Reed94, Tillman99], in green algae [Dennis91, Metzger05], in fungi [Strobel08] and in bacteria [Oro67, Bagaeva04], especially cyanobacteria, which produce mostly pentadecane and heptadecane [Winters69, McInnes80, Dembitsky02].
The alkanes are typically produced from long-chain and very-long chain (20-34) fatty acids that are produced from the "standard" C16 and C18 fatty acids by specialized fatty acid synthases, known as elongases (see very long chain fatty acid biosynthesis I). These fatty acids are converted to alkanes in three steps - activation of the fatty acid by an acyl-carrier-protein or coenzyme A, reduction of the activated fatty acid to an aldehyde, and decarbonylation of the aldehyde, resulting in an alkane that is one carbon short of the original fatty acid [Cheesbrough88, Dennis92, Kunst03]. Since most fatty acids have an even number of carbons (fatty acids are synthesized by the addition of two carbon units), the resulting alkanes have an odd number of carbons.
Botryococcus braunii BOT88-2 produces alkanes when grown anaerobically. The pathway leading to alkane production begins with fatty acids that are activated to a CoA derivative and reduced to aldehydes by an NADH-dependent acyl-CoA reductase (NADH) [Dennis91, Wang95]. The aldehydes are decarbonylated into alkanes by an aldehyde decarbonylase, a cobalt-depndent, integral membrane protein [Dennis92]. Unlike cyanobacterial decarbonylases that produce formate [Warui11], the decarbonylases from higher plants and green algae produce carbon monoxide [Dennis92, SchneiderBelhad00].
Cheesbrough88: Cheesbrough TM, Kolattukudy PE (1988). "Microsomal preparation from an animal tissue catalyzes release of carbon monoxide from a fatty aldehyde to generate an alkane." J Biol Chem 263(6);2738-43. PMID: 3343228
Dembitsky02: Dembitsky VM, Srebnik M (2002). "Variability of hydrocarbon and fatty acid components in cultures of the filamentous cyanobacterium Scytonema sp. isolated from microbial community "black cover" of limestone walls in Jerusalem." Biochemistry (Mosc) 67(11);1276-82. PMID: 12495426
Dennis91: Dennis MW, Kolattukudy PE (1991). "Alkane biosynthesis by decarbonylation of aldehyde catalyzed by a microsomal preparation from Botryococcus braunii." Arch Biochem Biophys 287(2);268-75. PMID: 1898004
McInnes80: McInnes, A. G., Walter, J. A., Wright, J. L. C. (1980). "Biosynthesis of hydrocarbons by algae: Decarboxylation of stearic acid to N-heptadecane in Anacystis nidulans determined by 13C- and 2H-labeling and 13C nuclear magnetic resonance." Lipids 15, 609.
Metzger90: Metzger, P., Allard, B., Casadevall, E., Berkaloff, C., Coute, A. (1990). "Structure and chemistry of a new chemical race of Botryococcus braunii (chlorophyceae) that produces lycopadiene, a tetraterpenoid hydrocarbon." J. Phycol. 26: 258.
Reed94: Reed JR, Vanderwel D, Choi S, Pomonis JG, Reitz RC, Blomquist GJ (1994). "Unusual mechanism of hydrocarbon formation in the housefly: cytochrome P450 converts aldehyde to the sex pheromone component (Z)-9-tricosene and CO2." Proc Natl Acad Sci U S A 91(21);10000-4. PMID: 7937826
SchneiderBelhad00: Schneider-Belhaddad F, Kolattukudy P (2000). "Solubilization, partial purification, and characterization of a fatty aldehyde decarbonylase from a higher plant, Pisum sativum." Arch Biochem Biophys 377(2);341-9. PMID: 10845712
Strobel08: Strobel GA, Knighton B, Kluck K, Ren Y, Livinghouse T, Griffin M, Spakowicz D, Sears J (2008). "The production of myco-diesel hydrocarbons and their derivatives by the endophytic fungus Gliocladium roseum (NRRL 50072)." Microbiology 154(Pt 11);3319-28. PMID: 18957585
Warui11: Warui DM, Li N, Norgaard H, Krebs C, Bollinger JM, Booker SJ (2011). "Detection of Formate, Rather than Carbon Monoxide, As the Stoichiometric Coproduct in Conversion of Fatty Aldehydes to Alkanes by a Cyanobacterial Aldehyde Decarbonylase." J Am Chem Soc. PMID: 21341652
Fulda02: Fulda M, Shockey J, Werber M, Wolter FP, Heinz E (2002). "Two long-chain acyl-CoA synthetases from Arabidopsis thaliana involved in peroxisomal fatty acid beta-oxidation." Plant J 32(1);93-103. PMID: 12366803
Ioki12: Ioki M, Baba M, Bidadi H, Suzuki I, Shiraiwa Y, Watanabe MM, Nakajima N (2012). "Modes of hydrocarbon oil biosynthesis revealed by comparative gene expression analysis for race A and race B strains of Botryococcus braunii." Bioresour Technol 109;271-6. PMID: 22257857
Lewin01: Lewin TM, Kim JH, Granger DA, Vance JE, Coleman RA (2001). "Acyl-CoA synthetase isoforms 1, 4, and 5 are present in different subcellular membranes in rat liver and can be inhibited independently." J Biol Chem 276(27);24674-9. PMID: 11319232
Malhotra99: Malhotra KT, Malhotra K, Lubin BH, Kuypers FA (1999). "Identification and molecular characterization of acyl-CoA synthetase in human erythrocytes and erythroid precursors." Biochem J 344 Pt 1;135-43. PMID: 10548543
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
Schnurr02: Schnurr JA, Shockey JM, de Boer GJ, Browse JA (2002). "Fatty acid export from the chloroplast. Molecular characterization of a major plastidial acyl-coenzyme A synthetase from Arabidopsis." Plant Physiol 129(4);1700-9. PMID: 12177483
Shockey02: Shockey JM, Fulda MS, Browse JA (2002). "Arabidopsis contains nine long-chain acyl-coenzyme a synthetase genes that participate in fatty acid and glycerolipid metabolism." Plant Physiol 129(4);1710-22. PMID: 12177484
Watkins96: Watkins PA, Howard AE, Gould SJ, Avigan J, Mihalik SJ (1996). "Phytanic acid activation in rat liver peroxisomes is catalyzed by long-chain acyl-CoA synthetase." J Lipid Res 37(11);2288-95. PMID: 8978480
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