Perrier Josette, Durand Anne, Giardina Thierry, Puigserver Antoine
Institut Méditerranéen de Recherche en Nutrition, Inra-UMR 1111 service 342, Université Paul Cézanne, Aix-Marseille, Faculté des Sciences et Techniques, Avenue Escadrille Normandie Niemen, F-13397 Marseille cedex 20, France.
Biochimie. 2005 Aug;87(8):673-85. doi: 10.1016/j.biochi.2005.04.002.
Protein acylation processes involve the covalent attachment of acyl moieties to the alpha- and epsilon-amino groups of polypeptide chains. The N-terminal blocking of proteins occurs in a wide range of eukariotic cells, where more than 50% of the cytosolic proteins can be N-alpha-acetylated. The acetylation which occurs during or after the biosynthesis of the polypeptide chains serves to protect the intracellular proteins from proteolysis. Food processing can also generate N-alpha-acetylated proteins and peptides. The mechanism underlying the intracellular catabolism of N-acetylated proteins has not yet been elucidated, however. It is generally assumed that two enzymes are involved in the hydrolysis of the N-terminal part of the proteins. The NH(2)-blocked peptides generated during proteolysis may be cleaved by an N-acylpeptide hydrolase (APH). This releases the N-terminal amino acid, which is in turn deacetylated by an aminoacylase, the most common of which is aminoacylase 1 (ACY 1). The corresponding free amino acid is therefore available for protein synthesis. Both APH and ACY 1 are cytoplasmic enzymes, which have been isolated from various mammalian tissues. APH belongs to a novel class of serine-type peptidases called the prolyl oligopeptidase (PROP) family. ACY 1 belongs to the M20 metalloenzyme family. In this review, the processes involved in alpha- and epsilon-acetylation and the catabolism of endogenous proteins and proteins involved in food processing are discussed. We then focus on the characteristics of the APH and ACY 1 enzymes involved in the final release of the free amino acids, which are essential to protein synthesis.
蛋白质酰化过程涉及酰基部分与多肽链的α-氨基和ε-氨基的共价连接。蛋白质的N端封闭在多种真核细胞中发生，其中超过50%的胞质蛋白可被N-α-乙酰化。在多肽链生物合成期间或之后发生的乙酰化作用是为了保护细胞内蛋白质不被蛋白水解。食品加工也可产生N-α-乙酰化的蛋白质和肽。然而，N-乙酰化蛋白质的细胞内分解代谢的潜在机制尚未阐明。一般认为有两种酶参与蛋白质N端部分的水解。蛋白水解过程中产生的NH₂封闭的肽可能被N-酰基肽水解酶（APH）切割。这会释放出N端氨基酸，该氨基酸继而被氨基酰化酶去乙酰化，其中最常见的是氨基酰化酶1（ACY 1）。因此相应的游离氨基酸可用于蛋白质合成。APH和ACY 1都是胞质酶，已从多种哺乳动物组织中分离出来。APH属于一类名为脯氨酰寡肽酶（PROP）家族的新型丝氨酸型肽酶。ACY 1属于M20金属酶家族。在本综述中，讨论了α-和ε-乙酰化过程以及内源性蛋白质和食品加工中涉及的蛋白质的分解代谢。然后我们重点关注参与游离氨基酸最终释放的APH和ACY 1酶的特性，这些游离氨基酸对蛋白质合成至关重要。
