OH O H O OH OH H2N + + Arg145 H2N + His69 H His196 H OH N 2+ Zn O Glu72 C H2N His196 O His69 H O + H2N NH2 N H N Arg127 OH 2+ Glu270 O Glu72 + H2N NH2 N Arg127 H2N O H Zn O Arg145 N N O H N H H His69 O H N 2+ Zn Ruptura Glu72 H C O His196 O Glu270 N H H O H O O + H2N NH2 Glu270 N Arg127 O O C 129 N H