Moura-da-Silva A M, Della-Casa M S, David A S, Assakura M T, Butera D, Lebrun I, Shannon J D, Serrano S M T, Fox J W
Laboratório de Imunopatologia, Instituto Butantan, SP 05503-900, São Paulo, Brazil.
Arch Biochem Biophys. 2003 Jan 15;409(2):395-401. doi: 10.1016/s0003-9861(02)00598-2.
The reprolysin subfamily of metalloproteinases includes snake venom metalloproteinases (SVMP) and mammalian disintegrin/metalloproteinase. These proteins are synthesized as zymogens and undergo proteolytic processing resulting in a variety of multifunctional proteins. Jararhagin is a P-III SVMP isolated from the venom of Bothrops jararaca. In crude venom, two forms of jararhagin are typically found, full-length jararhagin and jararhagin-C, a proteolytically processed form of jararhagin that is composed of the disintegrin-like and cysteine-rich domains of jararhagin. To better understand the structural and mechanistic bases for these forms of jararhagin in the venom of B. jararaca and the source of venom complexity in general, we have examined the jararhagin forms isolated from venom and the autolysis of isolated jararhagin under the conditions of varying pH, calcium ion concentration, and reducing agents. From our results, jararhagin isolated from venom appears as two forms: a predominant form that is stable to in vitro autolysis and a minor form that is susceptible to autolysis under a variety of conditions including alkaline pH, low calcium ion concentrations, or reducing agent. The autolysis site for production of jararhagin-C from isolated jararhagin was different from that observed for jararhagin-C as isolated from crude venom. Taken together, these data lead us to the conclusion that during the biosynthesis of jararhagin in the venom gland at least three forms are present: one form which is rapidly processed to give rise to jararhagin-C, one form which is resistant to processing in the venom and autolysis in vitro, and one minor form which is susceptible to autolysis under conditions that promote destabilization of its structure. The presence of these different forms of jararhagin contributes to greater structural and functional complexity of the venom and may be a common feature among all snake venoms. The biological and biochemical features in the venom gland responsible for these jararhagin isoforms are currently under investigation.
金属蛋白酶的解聚素亚家族包括蛇毒金属蛋白酶（SVMP）和哺乳动物的解整合素/金属蛋白酶。这些蛋白质以酶原形式合成，并经过蛋白水解加工，产生多种多功能蛋白质。矛头蝮蛇毒金属蛋白酶是从巴西矛头蝮蛇毒液中分离出的一种P-III型蛇毒金属蛋白酶。在粗毒液中，通常可发现两种形式的矛头蝮蛇毒金属蛋白酶，即全长矛头蝮蛇毒金属蛋白酶和矛头蝮蛇毒金属蛋白酶-C，后者是经过蛋白水解加工的矛头蝮蛇毒金属蛋白酶形式，由矛头蝮蛇毒金属蛋白酶的解整合素样结构域和富含半胱氨酸的结构域组成。为了更好地理解巴西矛头蝮蛇毒液中这些形式的矛头蝮蛇毒金属蛋白酶的结构和作用机制基础以及毒液复杂性的一般来源，我们研究了从毒液中分离出的矛头蝮蛇毒金属蛋白酶形式以及在不同pH值、钙离子浓度和还原剂条件下分离出的矛头蝮蛇毒金属蛋白酶的自溶情况。根据我们的研究结果，从毒液中分离出的矛头蝮蛇毒金属蛋白酶呈现出两种形式：一种主要形式对体外自溶稳定，另一种次要形式在包括碱性pH值、低钙离子浓度或还原剂在内的多种条件下易发生自溶。从分离出的矛头蝮蛇毒金属蛋白酶产生矛头蝮蛇毒金属蛋白酶-C的自溶位点与从粗毒液中分离出的矛头蝮蛇毒金属蛋白酶-C的自溶位点不同。综合这些数据，我们得出结论，在毒腺中矛头蝮蛇毒金属蛋白酶的生物合成过程中至少存在三种形式：一种形式会迅速加工产生矛头蝮蛇毒金属蛋白酶-C，一种形式在毒液中对加工有抗性且在体外不易自溶，还有一种次要形式在促进其结构不稳定的条件下易发生自溶。这些不同形式的矛头蝮蛇毒金属蛋白酶的存在导致毒液具有更大的结构和功能复杂性，这可能是所有蛇毒的共同特征。目前正在研究毒腺中负责这些矛头蝮蛇毒金属蛋白酶同工型的生物学和生化特征。
