STRUCTURE/ PHARMACOLOGY OF KING COBRA DIPEPTIDYL PEPTIDASE IV & COTTONMOUTH VENOM

该提案包括使用类似方法的两个分提案。1.哺乳动物二肽基肽酶IV (DPP IV)是一种高度糖基化的丝氨酸蛋白酶，能从寡肽中释放N-末端二肽。它 是一种完整的膜蛋白(CD26)，也是一种血浆蛋白，其生理作用是 未知(Hosono et at.，1999)。在其不同的生理作用中，DPP IV去除了X-Pro、His-Ala或 神经肽Y和P物质等激素N末端的酪氨酸丙二肽。 豪尔赫·达席尔瓦和艾尔德(2000)在蛇毒中发现。民进党静脉输液在毒液中的作用可能是防止 被毒害的猎物部分通过失活血管收缩多肽而产生的高血压反应 荷尔蒙(Aird，2002)。它还可能导致人类毒液中出现的持续性低血压。 以及炎症。目前的研究应该有助于阐明人可溶性DPP IV的作用。 2.蛇毒分解磷酸酯的酶最初是在蛇毒 磷酸二酯酶(PDE)是由Gulland和Jackson(1938)报道的。尽管历史悠久，PDE的 毒液的作用一直是个谜，直到Aird(2002)提出它的功能可能是释放 内源性嘌呤，这将通过降压和抑制 神经递质释放。蛇毒PDE因其在核方面的应用而引起了人们极大的兴趣 酸研究(&gt；2400篇Medline引文)。尽管它接近试剂状态，但其结构尚不清楚。多数 PDE的形式是膜结合的或胞浆的，而毒液PDE是极易溶的，因此 在被捕食生物的胞外液中发挥作用。它具有广泛的底物特异性[Razzell和Khorana， 1959；Laskowski，1980]，使其非常适合于从各种类型的腺苷核苷酸中快速释放 寡核苷酸前体，毒化的中心主题(Aird，2002)。它也有焦磷酸酶 活性[Laskowski，1980]，从核苷三磷酸盐中释放核苷酸和焦磷酸。 核苷酸被5‘-核苷酸酶迅速降解为核苷，这种酶存在于毒液和猎物中。 纸巾。毒液PDE是第一个被报道具有苏氨酸形成共价键的活性部位的酶 (磷酸化)中间体[Burgers等人，1979；Gulp和Butler，1986]。这些功能 特征表明，它很可能在结构上是独一无二的。

This proposal comprises two subproposals that use similar methods. 1. Mammalian dipeptidyl peptidase IV (DPP IV) is a highly glycosylated serine protease, that releases N-terminal dipeptides from oligopeptides. It is both an integral membrane protein (CD26) and a plasma protein, the physiological role of which is unknown (Hosono et at., 1999). Among its diverse physiological roles, DPP IV removes X-Pro, His-Ala or tyr-Ala dipeptides from the N-termini of hormones such as neuropeptide Y and substance P. It was discovered in snake venoms by Jorge da Silva and Aird (2000). DPP IVs role in venom may be to prevent a hypertensive response on the part of the envenomated prey by inactivating vasoconstrictive peptidyl hormones (Aird, 2002). It may also contribute to the persistent hypotension seen in human envenomation and to inflammation. The present study should shed light on the role of human soluble DPP IV. 2. Snake venom enzymes that cleave phosphate esters were first discovered when venom phosphodiesterase (PDE) was reported by Gulland and Jackson (1938). Despite this long history, PDE's role in envenomation remained enigmatic until Aird (2002) proposed that its function might be to release endogenous purines, which would immobilize the prey via hypotension and suppression of neurotransmitter release. Snake venom PDE has attracted great interest because of its utility in nucleic acid studies (>2,400 Medline citations). Despite its near reagent status, its structure is unknown. Most forms of PDE are membrane-bound or cytosolic, whereas venom PDE is extremely soluble, so as to function in the extracellular fluid of prey organisms. It has broad substrate specificity [Razzell and Khorana, 1959; Laskowski, 1980], making it well suited to the rapid liberation of adenosine nucleotides from various oligonucleotide precursors, a central theme in envenomation (Aird, 2002). It also has pyrophosphatase activity [Laskowski, 1980], releasing nucleotides and pyrophosphate from nucleoside triphosphates. Nucleotides are rapidly degraded to nucleosides by 5'-nuc!eotidase, present in both venom and prey tissues. Venom PDE was the first enzyme reported to have an active site threonine forming a covalent (phosphorylated) intermediate [Burgers et al., 1979; Gulp and Butler, 1986]. These functional characteristics suggest that it is likely to be structurally unique.