Lee K H, Hong S Y, Oh J E
Protein Chemistry Laboratory, Mogam Biotechnology Research Institute, Yongin-City, South Korea.
FEBS Lett. 1998 Nov 13;439(1-2):41-5. doi: 10.1016/s0014-5793(98)01333-7.
Tenecin 1, an inducible antibacterial protein secreted in the larvae of Tenebrio molitor, has a long N-terminal loop and common structural feature of insect defensin family corresponding to cysteine stabilized alpha/beta motif. To study the function of the N-terminal loop and disulfide bridges, N-terminal loop deleted tenecin 1, reduced tenecin 1 and tenecin 1 were chemically synthesized and their activities were measured. N-terminal loop deleted tenecin and reduced tenecin 1 did not show antibacterial activity. Circular dichroism (CD) spectroscopy data revealed that the alpha-helical content of tenecin 1 and the other proteins increased in the presence of 50% (v/v) trifluoroethanol (TFE) and the alpha-helical content of tenecin 1 was much higher than that of the other proteins in buffer with or without 50% (v/v) TFE. These results suggest that disulfide bridges are necessary for the activity structure and the N-terminal loop plays an important role in the increase of alpha-helix in the membrane mimetic environment and the activity.
天牛素1是一种在黄粉虫幼虫中分泌的可诱导抗菌蛋白，具有长的N端环以及昆虫防御素家族对应于半胱氨酸稳定的α/β基序的共同结构特征。为了研究N端环和二硫键的功能，化学合成了N端环缺失的天牛素1、还原型天牛素1和天牛素1，并测定了它们的活性。N端环缺失的天牛素和还原型天牛素1均未表现出抗菌活性。圆二色（CD）光谱数据显示，在50%（v/v）三氟乙醇（TFE）存在下，天牛素1和其他蛋白质的α-螺旋含量增加，并且在有或没有50%（v/v）TFE的缓冲液中，天牛素1的α-螺旋含量远高于其他蛋白质。这些结果表明，二硫键对于活性结构是必需的，并且N端环在模拟膜环境中α-螺旋的增加和活性方面发挥重要作用。
