Cardiotoxin Analog (CTX) IV 6-12

Cardiotoxin Analog (CTX) IV 6-12 is a peptide fragment of cyclophosphamide analog (CTX) IV, derived from the venom of Naja atra, and is a unique cardiotoxin analog^[1]. Cardiotoxin Analog (CTX) IV 6-12 has a three-finger ring structure similar to neurotoxins and muscarinic toxins and has cytolytic effects on many cells^[2]. Cardiotoxin Analog (CTX) IV 6-12 can cause depolarization and contraction of smooth and skeletal muscles, as well as depolarization of nerve cells^[3]. Cardiotoxin Analog (CTX) IV 6-12 is able to induce membrane fusion of vesicles formed by phospholipids such as cardiolipin or sphingomyelin^[4]. Cardiotoxin Analog (CTX) IV 6-12 is the only cardiotoxin isoform known to date that has a positively charged residue at the N-terminal amino acid^[5]. CTX IV differs from CTX II only by the presence of arginine in place of a leucine residue at position 1^[6].

References:
[1] Kaneda N, Sasaki T, Hayashi K. Primary structures of cardiotoxin analogues II and IV from the venom of Naja naja atra[J]. Biochimica et Biophysica Acta (BBA)-Protein Structure, 1977, 491(1): 53-66.
[2] Wu W G. Diversity of cobra cardiotoxin[J]. Journal of Toxicology: Toxin Reviews, 1997, 16(3): 115-134.
[3] Harvey A L. Cardiotoxins from cobra venoms: possible mechanisms of action[J]. Journal of Toxicology: Toxin Reviews, 1985, 4(1): 41-69.
[4] Forouhar F, Huang W N, Liu J H, et al. Structural basis of membrane-induced cardiotoxin A3 oligomerization[J]. Journal of Biological Chemistry, 2003, 278(24): 21980-21988.
[5] Jang J Y, Kumar T K S, Jayaraman G, et al. Comparison of the hemolytic activity and solution structures of two snake venom cardiotoxin analogues which only differ in their N-terminal amino acid[J]. Biochemistry, 1997, 36(48): 14635-14641.
[6] Kumar T K S, Pandian S T K, Jayaraman G, et al. Understanding the structure, function and folding of cobra toxins[J]. PROCEEDINGS-NATIONAL SCIENCE COUNCIL REPUBLIC OF CHINA PART A PHYSICAL SCIENCE AND ENGINEERING, 1999, 23: 1-19.

Cardiotoxin Analog (CTX) IV 6-12是环磷酰胺类似物（CTX）IV的一部分肽，来源于Naja atra（台湾眼镜蛇）的毒液，是一种独特的心脏毒素类似物^[1]。Cardiotoxin Analog (CTX) IV 6-12具有类似于神经毒素和毒蕈碱毒素的三指环结构，对许多细胞具有溶细胞作用^[2]。Cardiotoxin Analog (CTX) IV 6-12能够引起平滑肌和骨骼肌的去极化和挛缩，以及神经细胞的去极化^[3]。Cardiotoxin Analog (CTX) IV 6-12能够诱导由磷脂（例如心磷脂或鞘磷脂）形成的囊泡的膜融合^[4]。Cardiotoxin Analog (CTX) IV 6-12是迄今为止已知的唯一在N-末端氨基酸处具有带正电荷残基的心脏毒素同种型^[5]。CTX IV与CTX II的唯一区别是，第1位上的亮氨酸残基被精氨酸取代^[6]。