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

眼镜王蛇二肽基肽酶 IV 的结构/药理学

• 批准号: 7547686
• 负责人: STEVEN D AIRD
• 金额: $ 10.83万
• 依托单位: NORFOLK STATE UNIVERSITY
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7547686
• 关键词: enzyme activity; minority institution research support; protein structure function; reptile poison; serine proteinases

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.

本提案包括两个使用类似方法的子提案。1.哺乳动物二肽基肽酶IV (DPP IV）是高度糖基化的丝氨酸蛋白酶，其从寡肽释放N-末端二肽。它 是一种整合的膜蛋白（CD 26）和血浆蛋白，其生理作用是 未知（Hosono et at.，1999年）。在其多种生理作用中，DPP IV去除X-Pro、His-Ala或 来自激素如神经肽Y和P物质的N-末端的tyr-Ala二肽。 Jorge da Silva和Aird（2000）在蛇毒中发现的。DPP IV在毒液中的作用可能是防止 一种高血压的反应对部分envenomed猎物通过灭活血管收缩肽 激素（Aird，2002）。它也可能有助于在人类毒液蛰入中观察到的持续性低血压 和炎症。本研究应阐明人可溶性DPP IV的作用。 2.切割磷酸酯的蛇毒酶首次被发现时， 磷酸二酯酶（PDE）由Gulland和杰克逊（1938）报道。尽管历史悠久，PDE 在艾尔德（2002年）提出其功能可能是释放毒液之前，毒液在毒液中的作用一直是个谜。 内源性嘌呤，通过低血压和抑制 神经递质释放蛇毒PDE因其在核酸检测中的应用而引起人们极大的兴趣， 酸研究（> 2，400 Medline引文）。尽管它接近试剂状态，但其结构尚不清楚。最 PDE的形式是膜结合的或胞质的，而毒液PDE是非常可溶的，以便 在被捕食生物的细胞外液中发挥作用。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细胞中快速释放腺苷核苷酸。 寡核苷酸前体，毒液蛰入的中心主题（Aird，2002）。它也有焦磷酸酶 活性[Laskowski，1980]，从核苷三磷酸释放核苷酸和焦磷酸。 核苷酸被5 '-nuc快速降解为核苷。在毒液和猎物中都有核苷酸酶 组织中毒液PDE是第一个被报道具有活性位点苏氨酸形成共价键的酶。 （磷酸化）中间体[Burgers等人，1979; Gulp和Butler，1986]。这些功能 这些特征表明，它在结构上可能是独特的。