SPERMINE對質體pBR322立體構造之效應

Abstract

中文摘要 最近二十年來，大家對生物體內的polyamines愈來愈感興趣。po1yamines包括二價的putrescine、三價的spermidine、與四價的spermine，它們的獨特功用目前還不甚清楚，但由於分佈廣泛，在細胞內濃度高，且在快速生長的組織中，量有顯著的增加，因此，有關這方面的研究愈來愈多。 關於polyamines，目前最迫切想知道的是：它們所扮演的生理角色以及作用機制。其最明顯的特徵在於擁有多價正電荷，因此，對酸性物質，比Na＋、K＋、Mg2+、Ca2+，或monoamine，具有更高的親和力，這種特質對帶四價正電的spermine尤其重要。 本實驗中，以spermine處理supercoil pBR322,經CD spectroplarimeter分析，得到與控制組幾乎相反的圖譜，顯示出spermine可引起pBR 322的結構改變，但我們仍然無法確知pBR322的結構到底發生了何種變化，只能推測它可能是一種Z-DNA like的結構。

ABSTRACT Interest has been increasing during the last twenty years in the naturally occurring polyamines, putrescine (1，4-diaminohutane), spermidine, and spermine. Their specific function is still obscure, but their ubiquitous distribution, their high concentration in cells, and the increase in the concentrations found in rapidly growing tissues have stimulated many investigations on these compounds. The most pressing questions in the polyamine field are: What is the physiological role of the polyamines, and what is the mechanism of their action The most obvious specific characteristic of the polyamins is their polybasic character, which gives them a much higher affinity for acidic constitutents than that exhibited by Na+, K+, Mg2+, Ca2+, or monoamines; this polybasic character is most pronounced with spermine because of its four positive groups. It seems very likely that the polybasic nature of the polyamines is very important in determining their physiological action. In this experiment, the spermine treated supercoil pBR322 produced a near-inversion of the UV circular dichroism spectrum, indicated that the spermine can induce conformation change of pBR322, but we still do not know what conformation it changed into, we just infer that it may be a z-DNA like conformation.