Koc Ahmet, Gladyshev Vadim N
Department of Biology, Izmir Institute of Technology, 35430 Urla, Izmir, Turkey.
Ann N Y Acad Sci. 2007 Apr;1100:383-6. doi: 10.1196/annals.1395.042.
Aging has been described for multicellular and asymmetrically dividing organisms, but the mechanisms are poorly understood. Oxidation of proteins is considered to be one of the major factors that leads to aging. Oxidative damage to proteins results in the oxidation of certain amino acid residues, among which oxidation of sulfur-containing amino acids, methionine and cysteine, is notable because of the susceptibility of these residues to damage, and occurrence of repair mechanisms. Methionine sulfoxide reductases, MsrA and MsrB, are thioredoxin-dependent oxidoreductases that reduce oxidized forms of methionine, methionine sulfoxides, in a stereospecific manner. These enzymes are present in all cell types and have shown to be regulating life spans in mammals, insects, and yeast. Here, their roles in modulating yeast life span are discussed.
衰老现象在多细胞且进行不对称分裂的生物体中已有描述，但相关机制仍知之甚少。蛋白质氧化被认为是导致衰老的主要因素之一。蛋白质的氧化损伤会导致某些氨基酸残基发生氧化，其中含硫氨基酸（甲硫氨酸和半胱氨酸）的氧化尤为显著，这是因为这些残基易受损伤，且存在修复机制。甲硫氨酸亚砜还原酶MsrA和MsrB是依赖硫氧还蛋白的氧化还原酶，它们以立体特异性方式还原甲硫氨酸的氧化形式——甲硫氨酸亚砜。这些酶存在于所有细胞类型中，并已证明在调节哺乳动物、昆虫和酵母的寿命方面发挥作用。在此，将讨论它们在调节酵母寿命中的作用。
