4.2.2.18	additional information	no effect of Mg2+ and Co2+	
4.2.2.18	additional information	no or little affected by various cations	
4.2.2.18	additional information	no effect of Ca2+, Co2+, Mg2+, Mn2+, Zn2+	
4.2.2.18	Na+	the activity is enhanced by 65.2% in the presence of 1.5 M NaCl