Quistad G B, Nguyen Q, Bernasconi P, Leisy D J
Sandoz Agro Inc., Palo Alto, CA 94304.
Insect Biochem Mol Biol. 1994 Dec;24(10):955-61. doi: 10.1016/0965-1748(94)90132-5.
The potency of venom from Bracon hebetor against lepidopterous larvae has been known for over 40 years, but previous attempts to purify and characterize individual protein toxins have been largely unsuccessful. Three protein toxins were purified from venom of this small parasitic wasp and the amino acid sequences of 22-31 consecutive residues at the amino-terminus were determined. These relatively large toxins (apparent molecular mass 73 kDa) were labile under many isolation techniques, but anion-exchange chromatography allowed purification with retention of biological activity. Two purified toxins were quite insecticidal (LD50 < 0.3 microgram/g) when injected into six species of lepidopterous larvae. On a molar basis, one toxin (Brh-I) has the highest known biocidal activity against Heliothis virescens (LD50 = 2 pmol/g).
四十多年来，人们一直都知道麦蛾茧蜂毒液对鳞翅目幼虫具有毒性，但此前纯化和鉴定单个蛋白质毒素的尝试大多未成功。从这种小型寄生黄蜂的毒液中纯化出了三种蛋白质毒素，并测定了其氨基末端22 - 31个连续残基的氨基酸序列。这些相对较大的毒素（表观分子量73 kDa）在许多分离技术下不稳定，但阴离子交换色谱法可实现纯化并保留生物活性。将两种纯化毒素注射到六种鳞翅目幼虫体内时，它们都具有很强的杀虫活性（半数致死剂量LD50 < 0.3微克/克）。按摩尔计算，一种毒素（Brh - I）对棉铃虫具有已知最高的杀生物活性（LD50 = 2皮摩尔/克）。
