The increasing need to access and elaborate dynamic and heterogeneous information sources distributed over Internet calls for new models and paradigms for application design and development. The mobile agent paradigm promotes the design of applications where agents roam through Internet sites to locally access ad elaborate information and resources, possibly cooperating with each other. This paper focuses on mobile agent coordination, and discusses the TuCSoN coordination model for Internet applications based on mobile information agents. The model is based on the notion of tuple centre, a tuple-based interaction space associated to each site and to be used both for inter-agent cooperation and for accessing to local infromation sources. TuCSoN tuple centres enhance tuple spaces because their behaviour in response to communication events can be programmed. This can be used to deal with heterogeneity and dynamicity of the information sources, as well as to ensure some degree of global data integrity. The effectiveness of the TuCSoN model is shown by means of an application example in the area of Internet information retrieval.