Conjugation of therapeutic proteins to polymers is well established but most methods result in multi-site and multiple conjugation or crosslinking resulting in lack of orientation and loss of activity. Using an enzyme mediated conjugation method we have prepared well-defined protein-polymer conjugates using a model protein, green fluorescent protein (GFP) with diblock copolymers based on a several hydrophilic and hydrophobic biocompatible polymers. In this proposal we wish to determine the effects of block copolymer structure on the properties of aggregates formed by these polymers & conjugates with GFP in solution, to develop an understanding of the phase behaviour of these species. We will also study GFP-poly(N-isopropylacrylamide) a polymer which becomes less soluble as the temperature increases to observe changes in aggregation state based on polymer hydrophobicity.