Phytanic acid is a methyl-branched fatty acid present in the human diet. Due to its structure, degradation by beta-oxidation is impossible. Instead, phytanic acid is oxidized by alpha-oxidation, yielding pristanic acid. Despite many efforts to elucidate the alpha-oxidation pathway, it remained unknown for more than 30 years. In recent years, the mechanism of alpha-oxidation as well as the enzymes involved in the process have been elucidated. The process was found to involve activation, followed by hydroxylase, lyase and dehydrogenase reactions. Part, if not all of the reactions were found to take place in peroxisomes. The final product of phytanic acid alpha-oxidation is pristanic acid. This fatty acid is degraded by peroxisomal beta-oxidation. After 3 steps of beta-oxidation in the peroxisome, the product is esterified to carnitine and shuttled to the mitochondrion for further oxidation. Several inborn errors with one or more deficiencies in the phytanic acid and pristanic degradation have been described. The clinical expressions of these disorders are heterogeneous, and vary between severe neonatal and often fatal symptoms and milder syndromes with late onset. Biochemically, these disorders are characterized by accumulation of phytanic and/or pristanic acid in tissues and body fluids. Several of the inborn errors involving phytanic acid and/or pristanic acid metabolism have been characterized on the molecular level.

中文翻译：

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植酸和壬二酸的人体代谢。

植烷酸是人类饮食中存在的甲基支链脂肪酸。由于其结构，不可能通过β-氧化降解。取而代之的是，植烷酸通过α-氧化被氧化，产生了豆酸。尽管人们为阐明α-氧化途径做出了许多努力，但三十多年来一直未知。近年来，已经阐明了α-氧化的机理以及参与该过程的酶。发现该过程涉及活化，然后是羟化酶，裂解酶和脱氢酶反应。如果不是全部，则部分反应被发现是在过氧化物酶体中发生的。植烷酸α-氧化的最终产物是豆甾酸。该脂肪酸被过氧化物酶体β-氧化降解。在过氧化物酶体中经过3步的β-氧化后，该产物被酯化成肉碱，然后穿梭到线粒体中进一步氧化。已经描述了几种先天性错误，其中植酸和壬基酚降解存在一种或多种缺陷。这些疾病的临床表现是异质的，并且在严重的新生儿症状和常常是致命的症状以及较晚发作的轻度综合症之间有所不同。从生物化学上讲，这些疾病的特征在于植物酸和/或壬二酸在组织和体液中的积累。在分子水平上已经表征了涉及植烷酸和/或癸二酸代谢的一些先天性错误。并在严重的新生儿症状和通常是致命的症状以及较轻的综合征和迟发之间有所不同。从生物化学上讲，这些疾病的特征在于植物酸和/或壬二酸在组织和体液中的积累。在分子水平上已经表征了涉及植烷酸和/或癸二酸代谢的一些先天性错误。并在严重的新生儿症状和通常是致命的症状以及较轻的综合征和迟发之间有所不同。从生物化学上讲，这些疾病的特征在于植物酸和/或壬二酸在组织和体液中的积累。在分子水平上已经表征了涉及植烷酸和/或癸二酸代谢的一些先天性错误。