探討核磁共振技術所解出的蛋白質結構其堆疊程度和演化之關係

Abstract

核磁共振是用來解蛋白質三維結構的主要實驗方法之一。該技術通常用於解析較小的蛋白質。在先前的結果，我們已由結晶所解出的蛋白質中，觀察到結構堆疊程度和序列的保留程度存有一定相關性。藉由考慮或忽略複合體中其它的subunits，我們發現該蛋白質的結構堆疊程度會相近於它的胺基酸的保留程度。這結果顯示，蛋白質可能會傾向形成有或無其他分子伴隨的構形，進而在演化過程施加約束力。 在此篇研究，由核磁共振技術解出的蛋白質所組成的資料集中，藉由比較結構堆疊程度和序列的保留程度，我們發現與先前研究一致的結果。基於蛋白質的大小，我們觀察到結構屬性的一些明顯趨勢，可能在後續研究核磁共振所解出的蛋白質其結構堆疊程度時，能作為有用的指引。雖然核磁共振所解出的蛋白質結構，在過去常被認為大部分品質低落於結晶蛋白。但在我們的結果中，兩者結構差異性似乎並不顯著。本篇論文也許對研究核磁共振解出的蛋白質，其結構和演化間的關係有所幫助。

Nuclear Magnetic Resonance (NMR) is one of primary experimental methods to determine protein three-dimensional structures. This technique is usually used for smaller protein. In our previous study, we have observed that the structural packing profile has correlated to the sequence conservation profile of a protein determined by X-ray. By considering or ignoring other subunits in a complex, we found that the degree of structural packing of a protein will become closer to its conservation of residues. The result suggests that a protein may tend to form the conformation, which exerts constraints on its evolutionary processes, by accompanied with or without other molecules. Here, we find the consistent result that conforms our previous study in a dataset composed of NMR proteins. Based on protein size, we observe some obvious tendencies of structural properties that may be a useful guide for studying the structural packing of NMR proteins. Although NMR structures were viewed as being of generally lower quality than X-ray structures, in our result, the consequences show a small difference between the two kinds of structures. Our research may contribute to people who want to study the relationship between structure and evolution of NMR proteins.