Tonello F, Schiavo G, Montecucco C
Centro C.N.R. Biomembrane and Dipartimento di Scienze Biomediche, Universita di Padova, Italy.
Biochem J. 1997 Mar 1;322 ( Pt 2)(Pt 2):507-10. doi: 10.1042/bj3220507.
Tetanus neurotoxin was depleted of its catalytic Zn2+ ion, and the apotoxin was reconstituted with different transition metal ions. The Mn2+- and Co2+-tetanus neurotoxins are highly active in the proteolysis of vesicle-associated membrane protein/synaptobrevin, the natural substrate of this toxin, whereas Cu2+ and Fe2+ minimally supported proteolytic activity. The visible absorbance spectrum of Co2+-tetanus neurotoxin shows a maximum at 538 nm with a molar absorption coefficient of 82 M(-1) x cm(-1). These results indicate that the Zn2+ environment at the active site of tetanus neurotoxin is different from those of known Zn2+-endopeptidases and provide a structural basis for the definition of tetanus neurotoxin, and the related clostridial neurotoxins, as an independent family of metalloproteases.
破伤风神经毒素中的催化锌离子被去除，脱辅基毒素再与不同的过渡金属离子重组。锰离子和钴离子修饰的破伤风神经毒素在对该毒素的天然底物——囊泡相关膜蛋白/突触小泡蛋白进行蛋白水解时具有高活性，而铜离子和亚铁离子对蛋白水解活性的支持作用极小。钴离子修饰的破伤风神经毒素的可见吸收光谱在538纳米处有最大值，摩尔吸收系数为82 M⁻¹·cm⁻¹。这些结果表明，破伤风神经毒素活性位点处的锌离子环境与已知的锌离子内肽酶不同，为将破伤风神经毒素以及相关的梭菌神经毒素定义为一个独立的金属蛋白酶家族提供了结构基础。
