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標題: | 澳州紅腹黑蛇神經毒素在神經鍵體上之專一性結合 |
作者: | 高又雅 |
出版年 : | 1994 |
學位: | 碩士 |
摘要: | Pseudexin B是由澳洲紅腹黑蛇(Pseudechis porphyriacus)純化出來的神經毒素,碘化後的pseudexin B在天竺鼠大腦的神經鍵體上有專一性結合。此專一性結合在Scatchard plot上可分解成兩種不同之親和力,以Rosenthal圖形法可求得這兩個解離常數分別?:Kd1=1.2±0.05nM及Kd2=10±3nM ;最大結合量分別為:Bmax1=2±0.15pmol/mg of protein及Bmax2=77±3pmol/mg of protein。加熱或以proteases處理神經鍵體後125I-pseudexin B在神經鍵體上的結合量沒有明顯下降。此專一性結合會隨著一價正離子濃度的改變而升降,約在100mM的結合量最大。二價正離子中,鍶離子及鋇離子約可取代鈣離子,而鎂離子及鈷離子則否。 許多其他PLA2分子均可抑制125I-pseudexin B在神經鍵體上的結合,但β-bungarotoxin及 notexin則否。以化學串接試劑進行共價聯結實驗標示125I-pseudexin B在神經鍵體上的接受體,可看到一條分子量為40KDa的共價聯結體。以proteases處理後,此標示帶即消失。在結合實驗中可抑制125I-pseudexin B結合的PLA2分子,也可抑制此一標示帶的生成,且其抑制能力之強弱與結合實驗求得之趨勢一致。 Pseudexin B was purified from the venom of Pseudechis porphriacus, and then iodinated for study of its binding to membranes from the brain . Specific binding of 125I-pseudexin B to guinea pig synaptosomes was demonstrated , and the binding curve could be resolved into two families of binding sites with Kd1=1.2±0.05nM and Kd2=10±3nM .The maximal binding Capacities were Bmax1=2±0.15 and Bmax2=77±3pmol/mg of protein. The amount of 125I-pseudexin B bound to synaptosomes was dependent on monovalent cation concentrations and with optimal concentration about 100mM Na+. Sr2+ and Ba2+ could, while Mg2 + and Co2 + could not replace Ca2 + in the binding reaction. The synaptosome binding sites were not sensitive to proteases and heat. One major conjugate of 40KDa was obtained when 125I-pseudexinB was cross-linked to its binding sites on membranes of synaptosomes . One major conjugate of 40KDa was obtained. As in binding experiments, this conjugation was prevented by most snake venom PLA2, but β-bungarotoxin and notexin were not inhibitory. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76065 |
全文授權: | 未授權 |
顯示於系所單位: | 生化科學研究所 |
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