Agrawal Vishal, Kishan K V Radha
Institute of Microbial Technology, Sector 39-A, Chandigarh 160 036, India.
Curr Protein Pept Sci. 2003 Jun;4(3):195-206. doi: 10.2174/1389203033487207.
It was predicted that the folding space for various protein sequences is restricted and a maximum of 1000 protein folds could be expected. Although, there were about 648 folds identified, general functional features of individual folds is not thoroughly studied. We selected OB-fold, which is supposed to be an oligonucleotide and oligosaccharide binding fold to study the general functional features. OB-fold is a small beta-barrel fold formed from 5 strands connected by modulating loops. We observed consistently 2 or 3 loops on the same face of barrel acting as clamps to bind to their ligands. Depending on the ligand, which could be a single or double stranded DNA/RNA or an oligosaccharide, and their conformational properties the loops change in length and sequence to accommodate various ligands. Different classes of OB-folded proteins were analyzed and found that the functional features are retained in spite of negligible sequence homology among various proteins studied.
据预测，各种蛋白质序列的折叠空间是有限的，预计最多有1000种蛋白质折叠形式。虽然已鉴定出约648种折叠形式，但对单个折叠形式的一般功能特征尚未进行深入研究。我们选择了OB折叠，它被认为是一种寡核苷酸和寡糖结合折叠形式，以研究其一般功能特征。OB折叠是一种由5条链通过调节环连接形成的小β桶状折叠。我们一致观察到，桶状结构同一面上有2或3个环充当夹子来结合其配体。根据配体（可以是单链或双链DNA/RNA或寡糖）及其构象性质，这些环的长度和序列会发生变化以容纳各种配体。对不同类别的OB折叠蛋白进行了分析，发现尽管所研究的各种蛋白质之间的序列同源性可忽略不计，但功能特征仍得以保留。
