nitrogenases

notecases

nucleases

nucleotidases

nutcases

oases

oligoclases

onchocerciases

orthoclases

outgases

overemphases

oxidases

oxidoreductases

oxyuriases

pancreases

paraphrases

pases

peases

pectases

pectinesterases

penicillinases

peptidases

periphrases

permeases

peroxidases

phases

phosphatases

phosphokinases

phospholipases

phosphorylases

photophases

phrases

pillowcases

pityriases

plagioclases

pleases

polymerases

prases

precreases

predeceases

prepurchases

prophases

protases

proteases

proteinases

psoriases

purchases

rases

rebases

reductases