2.7.1.15	-	640998, 640999, 641000, 641002, 672549, 673692, 760926, 761262	
2.7.1.15	by affinity chromatography on a nickel-chelating column and gel filtration	695385	
2.7.1.15	Ni2+-affinity and gel-filtration chromatography	760297	
2.7.1.15	using affinity chromatography	721227