Comparison of cyanide-degrading nitrilases

Engineering pH-tolerant mutants of a cyanide dihydratase

“…Compared with conventional methods to detoxify cyanide (Young and Jordan 1995), microbial treatment can be inexpensive and environmentally friendly (Dubey and Holmes 1995;Knowles 1988). Enzymes capable of degrading cyanide have been found in a few bacteria and numerous fungi and plants (Jandhyala et al 2005;Thuku et al 2009); our work focuses on those belonging to the nitrilase superfamily (Brenner 2002).…”

Cyanide-degrading nitrilases in nature

“…It is frequently referred to as a cyanidase and converts cyanide into ammonia and formate: HCN+ 2H 2 O AE NH 3 + HCOOH (Jandhyala et al, , 2005Watanabe et al, 1998). Structural similarities between these two groups of cyanide-degrading nitrilases and other nitrilases are abundant.…”

“…Hence, the native proteins have molecular masses ranging from 300 kDa to over 1 mDa depending upon species and conditions. The sequence conservation is generally quite high with a notable exception at the protein C-terminus that is highly variable (Jandhyala et al, 2005). Even among proteins from the same organism, strain types with otherwise Nitrilases are enzymes that hydrolyze the carbon-nitrogen triple bond (Pace and Brenner, 2001).…”

“…The first of these, cyanide hydratase (CHT), is found broadly throughout the fungal kingdom but best studied variants are from Neurospora crassa, Gloeocercospora sorghi and Fusarium lateritium (Basile et al, 2008;Fry and Munch 1975;Jandhyala et al, 2005). It converts cyanide into formamide as the product, HCN+ H 2 O AE CH 3 NO.…”

The Mechanism of the Amidases

“…strain KNK712, led to the proposal that the glutamate (equivalent to Glu-59) enhances the nucleophilicity of the cysteine enabling it to attack the carbonyl carbon of the amide. The proposal that the glutamate at this location enhances the nucleophilicity of the cysteine has found wide acceptance in the nitrilase and amidase literature (9,(12)(13)(14).…”