1.10.3.9	Ca2+	photosystem II contains a Mn4Ca cluster	716312	
1.10.3.9	Ca2+	PS II contains a redox active Mn4OxCa cluster	716441	
1.10.3.9	Ca2+	the enzyme possesses a Mn4Ca cluster, PSII can be inactivated through the depletion of Ca2+ or through loss of the Mn4Ca cluster	714358	
1.10.3.9	Fe2+	a high spin non-heme iron (Fe2+) is located between the two bound quinones QA and QB	714332	
1.10.3.9	Fe2+	nonheme Fe2+	726401	
1.10.3.9	Fe2+	the enzyme contains non-heme iron	714358	
1.10.3.9	Mn2+	photosystem II contains a Mn4Ca cluster	716312	
1.10.3.9	Mn2+	PS II contains a redox active Mn4OxCa cluster	716441	
1.10.3.9	Mn2+	the enzyme possesses a Mn4Ca cluster, PSII can be inactivated through loss of the Mn4Ca cluster	714358