Cysteine hydrolases; This family contains amidohydrolases, like CSHase (N-carbamoylsarcosine amidohydrolase), involved in creatine metabolism and nicotinamidase, converting nicotinamide to nicotinic acid and ammonia in the pyridine nucleotide cycle. It also contains isochorismatase, an enzyme that catalyzes the conversion of isochorismate to 2,3-dihydroxybenzoate and pyruvate, via the hydrolysis of the vinyl ether bond, and other related enzymes with unknown function.