Theaimofthisarticleistostudytheeffectivebehaviorofthesolutionofanonlinearproblemarisinginthemodellingofenzymecatalyzedreactionsthroughtheexteriorofadomaincontainingperiodicallydistributedreactivesolidobstacles,withperiodε.Theasymptoticbehaviorofthesolutionofsuchaproblemisgovernedbyanewellipticboundary-valueproblem,withanextrazero-ordertermthatcapturestheeffectoftheenzymaticreactions.