4.1.3.1	Ni2+	no activity in absence of exogenous cation, Ni2+ 7% as effective as Mg2+	33117	
4.1.3.1	Sr2+	no activation	33147, 33148	
4.1.3.1	Sr2+	no activity in absence of exogenous cation, Sr2+ 3% as effective as Mg2+	33117	
4.1.3.1	Zn2+	5 mM, 90% inhibition of Mg2+-activated enzyme, interaction with catalytic domain induces partial unfolding (revealed by thermal denaturation, far-UV circular dichroism, ANS fluorescence spectra, and glutaraldehyde crosslinking)	701127