Degradation of the metal-cyano complex tetracyanonickelate (II) by Fusarium oxysporum N-10

A fungus with the ability to utilize a metal-cyano compound, tetracyanonick elate (II) :K-2[Ni (CN)(4)]I TCN, as its sole source of nitrogen was isolat ed from soil and identified as Fusarium oxysporum N-10. Both intact mycelia and cell-free extract of the strain catalyzed hydrolysis of TCN to formate and ammonia and produced formamide as an intermediate, thereby indicating that a hydratase and an amidase sequentially participated in the degradatio n of TCN. The enzyme catalyzing the hydration of TCN was purified approxima tely ten-fold from the cell-free extract of strain N-10 with a yield of 29% . The molecular mass of the active enzyme was estimated to be 160 kDa. The enzyme appears to exist as a homotetramer, each subunit having a molecular mass of 40 kDa. The enzyme also catalyzed the hydration of KCN, with a cyan ide-hydrating activity 2x10(4) times greater than for TCN. The kinetic para meters for TCN and KCN indicated that hydratase isolated from F. oxysporum was a cyanide hydratase able to utilize a broad range of cyano compounds an d nitriles as substrates.