When is e used before a word?
You are quite right; I thought one word and typed another. The infinitive particle is 'ke'.
Having looked into this a little more, I can say that 'e' is also a marker of imperfective aspect (usually with 'ana' after the verb), and an agentive particle preceding a noun or pronoun in passive constructions using verb 'ia. There might well be other uses, too.