Answer:

METHIONYLTHREONYLTHREONYGLUTAMINYLARGINY

Explanation:

All told, the full chemical name for the human protein titin is 189,819 letters, and takes about three-and-a-half hours to pronounce. The problem with including chemical names is that there's essentially no limit to how long they can be.

Answer:

METHIONYLTHREONYLTHREONYGLUTAMINYLARGINYL