植物低分子量熱休克蛋白質的生理功能

Abstract

植物在高溫逆境下會合成大量的低分子量熱休克蛋白質(LMW HSPs)，在大豆中，此LMW HSPs 70-100％硫酸銨集濃分劃區內的蛋白質具有熱保護能力，可以使植物可溶性蛋白質在高溫下的變性量降低達50％，此LMW HSPs所保護的對象可能是與膜系統相關的蛋白質，而且沒有任何一種蛋白質受保護的情形較為明顯，不同離子強度對此熱保護作用並無顯著影響。為更進一步證實此熱保護能力來自LMW HSPs，而不是其他HSPs所造成的影響，故直接以純化的水稻LMW HSP融合蛋白質(fusion protein)進行熱保護實驗，結果證實LMW HSP的確能提供熱保護效應，而且熱保護能力會隨著所加入水稻LMW HSP融合蛋白質的增加而增加。除此之外，此熱保護能力在不同植物種類之間具有共通性；另一方面，也對LMW HSPs累積的量與熱保護能力之間的相關性作一探討。

Plants can produce a large amount of Low Molecular Weight heat shock proteins under heat stress. The LMW HSPs enriched 70-100% ammonium-sulphate fraction has the thermoprotection ability to prevent the soluble protein from denaturation under heat stress, and the protection efficiency can reach 50%. The LMW HSPs have the tendency to protect the membrane-related proteins but have no substrate-specificity. Different salt concentration has little effect on this thermoprotection ability. For further confirmation of the thermoprotection ability is mainly from the LMW HSPs, I used the purified rice LMW HSP fusion protein as LMW HSP donator and varified that the LMW HSP solely can contribute the thermoprotection ability to plants. I also found the protection efficiency is proportional to the amount of LMW HSPs added. Besides these, the thermoprotection ability is changeable among different kind of plants. On the other hand, I have tried to find out the relationship between the amount of LMW HSPs accumulation and the thermoprotection ability.