Higuchi Shigesada, Murayama Nobuhiro, Saguchi Ken-ichi, Ohi Hiroaki, Fujita Yoshiaki, da Silva Nelson Jorge, de Siqueira Rodrigo José Bezerra, Lahlou Saad, Aird Steven D
Showa University School of Pharmaceutical Sciences, Shinagawa-ku, Tokyo 142-8555, Japan.
Comp Biochem Physiol C Toxicol Pharmacol. 2006 Oct;144(2):107-21. doi: 10.1016/j.cbpc.2006.04.006. Epub 2006 Apr 28.
In crotaline venoms, angiotensin-converting enzyme inhibitors [ACEIs, also known as bradykinin potentiating peptides (BPPs)], are products of a gene coding for an ACEI/BPP-C-type natriuretic peptide (CNP) precursor. In the genes from Bothrops jararaca and Gloydius blomhoffii, ACEI/BPP sequences are repeated. Sequencing of a cDNA clone from venom glands of Crotalus durissus collilineatus showed that two ACEIs/BPPs are located together at the N-terminus, but without repeats. An additional sequence for CNP was unexpectedly found at the C-terminus. Homologous genes for the ACEI/BPP-CNP precursor suggest that most crotaline venoms contain both ACEIs/BPPs and CNP. The sequence of ACEIs/BPPs is separated from the CNP sequence by a long spacer sequence. Previously, there was no evidence that this spacer actually coded any expressed peptides. Aird and Kaiser (1986, unpublished) previously isolated and sequenced a peptide of 11 residues (TPPAGPDVGPR) from Crotalus viridis viridis venom. In the present study, analysis of the cDNA clone from C. d. collilineatus revealed a nearly identical sequence in the ACEI/BPP-CNP spacer. Fractionation of the crude venom by reverse phase HPLC (C(18)), and analysis of the fractions by mass spectrometry (MS) indicated a component of 1020.5 Da. Amino acid sequencing by MS/MS confirmed that C. d. collilineatus venom contains the peptide TPPAGPDGGPR. Its high proline content and paired proline residues are typical of venom hypotensive peptides, although it lacks the usual N-terminal pyroglutamate. It has no demonstrable hypotensive activity when injected intravenously in rats; however, its occurrence in the venoms of dissimilar species suggests that its presence is not accidental. Evidence suggests that these novel toxins probably activate anaphylatoxin C3a receptors.
在响尾蛇毒液中，血管紧张素转换酶抑制剂[ACEIs，也称为缓激肽增强肽（BPPs）]是编码ACEI/BPP - C型利钠肽（CNP）前体的基因产物。在锯鳞蝰和日本蝮的基因中，ACEI/BPP序列是重复的。对杜氏响尾蛇指名亚种毒腺cDNA克隆的测序表明，两个ACEIs/BPPs位于N端，且无重复。意外的是，在C端发现了一个额外的CNP序列。ACEI/BPP - CNP前体的同源基因表明，大多数响尾蛇毒液同时含有ACEIs/BPPs和CNP。ACEIs/BPPs的序列与CNP序列由一个长的间隔序列隔开。以前，没有证据表明这个间隔序列实际编码任何表达的肽。Aird和Kaiser（1986年，未发表）之前从草原响尾蛇毒液中分离并测序了一个11个残基的肽（TPPAGPDVGPR）。在本研究中，对杜氏响尾蛇指名亚种cDNA克隆的分析揭示了ACEI/BPP - CNP间隔序列中几乎相同的序列。通过反相高效液相色谱（C(18)）对粗毒液进行分级分离，并通过质谱（MS）对各组分进行分析，结果显示有一个1020.5 Da的组分。通过串联质谱进行氨基酸测序证实，杜氏响尾蛇指名亚种毒液含有肽TPPAGPDGGPR。尽管它缺乏通常的N端焦谷氨酸，但它的高脯氨酸含量和成对的脯氨酸残基是毒液降压肽的典型特征。当静脉注射到大鼠体内时，它没有明显的降压活性；然而，它在不同物种毒液中的出现表明它的存在并非偶然。有证据表明，这些新型毒素可能激活过敏毒素C3a受体。
