蛋白质空间结构属性与全基因组微生物耐热性的关系

 溶剂接触表面积、空腔个数和体积、紧密度、疏水性以及温度因子是影响蛋白质耐热的主要三维结构参数.挑选NCBI COG数据库中具有全基因组的单细胞微生物，选择其中三维结构已知的蛋白质作为研究对象，分析这些因素对细菌类和古细菌类微生物耐热性的影响.结果表明：（1）古细菌类蛋白质的空腔个数和体积与耐热性无关，极性面积和表面残基个数随耐热性增加而降低;（2）超高温细菌类蛋白质的分子量比较小，空腔个数和体积都小于常温蛋白质，而且空腔个数对稳定性的贡献大于空腔体积;（3）无论是古细菌还是细菌类蛋白质，疏水性和紧密度都不随耐热性变化，但暴露残基个数越多，蛋白质的耐热性越差;（4）两类蛋白质侧链的温度因子都高于主链，这与侧链的运动性（柔性）一般比主链高的实验结果一致；另外，超高温细菌类蛋白质的温度因子明显高于常温蛋白质.

Relationship Between Protein Structural Attributes and Complete Genome Microorganisms' Thermostability

Solvent accessible surface area,cavity numbers and volume,compactness,hydrophobicity and temperature factor are the major three-dimension structural parameters that contribute to protein thermostability.In this paper,we selected complete genome unicellular microorganisms from NCBI COG database,and collected all proteins whose three-dimensional structure had been measured to study the influence of these factors on protein thermostability(the proteins had been classified to bacterial proteins and archaeal proteins).The results show:(1) cavity numbers and volume have nothing to do with archaeal protein thermostability,but the polar area and surface residue numbers increase in the majority of the mesophilic proteins;(2) The molecular weight,cavity numbers and volume in hyperthermophilic bacterial proteins is smaller and less than in mesophilic proteins,and the contribution of cavity numbers to thermostability are larger than cavity volume;(3)Both thermophilic and mesophilic proteins have similar hydrophobicities and compactness,but the thermostability decrease when the surface residue numbers increase;(4)In both types of proteins,the temperature factor in side chains are higher than main chains,which accords to the fact that the flexibility in side chains is higher than main chains.On the other hand,the hyperthermophilic proteins have a greater content of temperature factors than mesophilic proteins.