Modified arginine deiminase

A compound comprising arginine deiminase covalently bonded via a linking group to polyethylene glycol,

• wherein the arginine deiminase is obtained from a microorganism selected from the group consisting of Streptococcus pyogenes, Streptococcus pneumoniae, Borrelia burgdorferi, Borrelia afzelii, Giardia intestinalis, Clostridium perfringens, Enterococcus faecalis, Lactobacillus sake, Bacillus licheniformis, and combinations thereof;
• wherein the polyethylene glycol has a total weight average molecular weight of from about 1,000 to about 40,000, and
• wherein the linking group is selected from the group consisting of a succinimide group, an amide group, an imde group, a carbamate group, an ester group, an epoxy group, a carboxyl group, a hydroxyl group, a carbohydrate, a tyrosine group, a cysteine group, a histidine group and combinations thereof.