Miseta A, Csutora P
Department of Clinical Chemistry, Faculty of Medicine, Pécs University, Pécs, Hungary.
Mol Biol Evol. 2000 Aug;17(8):1232-9. doi: 10.1093/oxfordjournals.molbev.a026406.
The occurrence and relative positions of cysteine residues were investigated in proteins of various species. Considering random mathematical occurrence for an amino acid coded by two codons (3. 28%), cysteine is underrepresented in all organisms investigated. Representation of cysteine appears to correlate positively with the complexity of the organism, ranging between 2.26% in mammals and 0. 5% in some members of the Archeabacteria order. This observation, together with the results obtained from comparison of cysteine content of various ribosomal proteins, indicates that evolution takes advantage of increased use of cysteine residues. In all organisms studied except plants, two cysteines are frequently found two amino acid residues apart (C-(X)(2)-C motif). Such a motif is known to be present in a variety of metal-binding proteins and oxidoreductases. Remarkably, more than 21% of all of cysteines were found within the C-(X)(2)-C motifs in ARCHEA.: This observation may indicate that cysteine appeared in ancient metal-binding proteins first and was introduced into other proteins later.
对不同物种蛋白质中半胱氨酸残基的出现情况及其相对位置进行了研究。考虑到由两个密码子编码的氨基酸的随机数学出现概率（3.28%），在所研究的所有生物体中，半胱氨酸的含量都低于预期。半胱氨酸的含量似乎与生物体的复杂性呈正相关，在哺乳动物中为2.26%，在古细菌目的某些成员中为0.5%。这一观察结果，连同从各种核糖体蛋白的半胱氨酸含量比较中获得的结果，表明进化利用了对半胱氨酸残基的更多使用。在除植物以外的所有研究生物体中，经常发现两个半胱氨酸相隔两个氨基酸残基（C-(X)(2)-C基序）。已知这种基序存在于多种金属结合蛋白和氧化还原酶中。值得注意的是，在古细菌中，超过21%的半胱氨酸存在于C-(X)(2)-C基序中。这一观察结果可能表明，半胱氨酸首先出现在古代金属结合蛋白中，随后被引入其他蛋白中。
