邱式鴻2006-07-252018-07-062006-07-252018-07-062004-11-30http://ntur.lib.ntu.edu.tw//handle/246246/10249眼睛的水晶體蛋白 (crystallins) 在長期受到紫外線、醣化 (glycation) 及氧 化 (oxidation) 的影響下失去結構的穩定性，進而凝集產生沉澱是形成白內障 (cataract) 的主要原因之一。α-水晶體蛋白在哺乳類動物水晶體蛋白組成中約佔 30%，含有兩種次單元蛋白，分別是 αA 與 αB 水晶體蛋白，其所具有的分子 保護者活性 (chaperone-like activity)，可能可以保護其它水晶體蛋白免於變性凝 集，暗示其與水晶體因老化而形成白內障有重大相關性。除此之外，α-水晶體蛋 白的組成分子之一的 αB-水晶體蛋白在其它器官組織中，尤其是心臟及骨骼 肌，被發現與細胞骨架 (cytoskeleton) 尤其是 intermediate filaments 的穩定性有 很大的關聯性。為探討 α-水晶體蛋白結構及功能的相關性，因此在本實驗室之 前的實驗中，已選殖並表現豬及土虱 αB-水晶體蛋白，並比較兩者之間的熱穩 定性、分子保護者活性及其他基本物化性質的差異，並嘗試解釋其與蛋白結構上 的關聯性，此部分結果業已發表。在本計畫年度中，我們對於豬及土虱 αB-水 晶體蛋白結構與功能的差異性上進行進一步的結構功能分析。經由保守性結構功 能區段交換的基因重組結果發現，αB-水晶體蛋白的功能決定結構並不意外的是 尤其保守性最高的 α-crystallin domain，包括熱穩定性、分子保護者活性以及其 他的物化特性。由於 α-crystallin domain 是小熱休克蛋白家族 (small heat shock protein family)的識別結構，因此未來仍可對 α-crystallin domain 進行近一步的結 構功能解析。Crystallins in the eyes would loss their structural stability and then aggregate because of UV damage, glycation, and oxidation during lifespan. Crystallin aggregation might be a major cause to cataract formation. α-Crystallin, a major protein of all vertebrate lenses (about 30%), consisting of two subunits αA and αB, could prevent other crystallin aggregations by its chaperone-like activity. It suggested that the chaperone-like activity of α-crystallin might be related to the cataract formation during aging. αB-crystallin, one subunit of α-crystallin, could be found in heart and muscle and other tissues. αB-crystallin was found to be functionally related to the stability of cytoskeletons, especially with intermediate filaments. In our previous studies, we cloned and expressed the recombinant αB-crystallins from porcine and catfish. The comparison studies were focused on the structural stability, chaperone-like activity, and other biophysical characteristics. We tried to explain the dependence of functional differences on structure. These results have been published. In this study, we have constructed the conserved domains chimeric mutants to explore the structure-function relationship directly. These results indicated that the determinant of functional differences was the α-crystallin domain, the most conserved domain in small heat shock protein family. The further studies on a-crystallin domain might give us detail mechanism of α-crystallin chaperone-like activity.application/pdf165264 bytesapplication/pdfzh-TW國立臺灣大學生化科學研究所水晶體蛋白分子保護者抗熱「保護者」活性老年性白內障熱休 克蛋白reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/10249/1/922311B002098.pdf