Biochemistry - The Chemical Reactions of Living Cells Volume 2 - D. Metzler 1980

Organization of Metabolism: Catabolic Pathways
Fatty Acid Oxidation
Oxidation of Saturated Hydrocarbons

While in fatty acid chains the oxidized end serves as the starting point for ß-Oxidation, The oxidation of saturated hydrocarbon chains cannot be initiated quite as easily. Nevertheless, our body Tissues are capable of metabolizing Hydrocarbons such as n-heptane, albeit very slowly. Certain microorganisms are able to rapidly oxidize straight-chain hydrocarbons; attempts have been made to select strains of Pseudomonas and Candida Yeasts that could be used to produce Single-Cell Protein from petroleum products [4].

The First stage in the oxidation of n-octane by Pseudomonas Bacteria is a hydroxylation reaction involving molecular oxygen (Ch. 10, Sect. F, 2, e), which leads to The formation of n-octanol [Equation (9-3)]. The subsequent oxidation of octanol to an acyl-CoA derivative, which presumably proceeds via the formation of an aldehyde [Equation

(9-3)], represents a typical Biological Oxidation reaction:

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Box 9-A

One of the Early Tracer Experiments

Long before The Development of radioisotope labeling techniques, Knoop in 1904 synthesized Fatty acids containing a covalently linked benzene ring at the end opposite to the carboxyl group as a marker. He synthesized labeled fatty acids with both even and odd numbers of carbon atoms in the straight chain and administered them in the diet of dogs. He then isolated two compounds from the dogs' urine: hippuric acid and phenylaceturic acid, which are Glycine amides of benzoic and phenylacetic acids, respectively. Knoop demonstrated that phenylacetic acid originated from fatty acids with an even number of carbon atoms, whereas benzoic acid came from fatty acids with an odd number of carbon atoms. From this, Knoop concluded that Fatty acid oxidation involves the sequential removal of two-carbon units at a time, leading to his famous theory of ß-oxidation.

Later experiments using isotopic tracers confirmed Knoop's Conclusions, but the Isolation of the corresponding Enzymes only became possible after 1950 with the discovery of coenzyme A (CoA). Subsequent studies on fatty acid oxidation using extracts from mitochondrial preparations rapidly led to the elucidation of the complete reaction pathway.