Like natural tropoelastin, polypeptides based on an elastin-like VPGXG repeat have a characteristic inverse temperature response, which leads to coacervate formation above a certain transition temperature and which could be useful for a variety of applications. The key advantage of elastin-like polypeptides (ELPs) over (tropo)elastin is a full control over this temperature response by adjustment of either the amino acid composition or the chain length, according to insights provided by extensive research. Future application of ELPs will require efficient ELP production systems, and in a previous article, we described the successful use of Pichia pastoris for secreted production of an ELP, with an overall yield of similar to 200 mg L-1. In this study, we investigated the influence of changed amino acid composition and chain length on the yield of secreted ELP. We have found that both parameters have a distinct impact on the overall yield, with higher yield for shorter and more hydrophilic ELPs. Because yield and transition temperature (Tt) thus appear to be positively correlated, we hypothesize that good solubility of ELP below the Tt promotes the secreted production and coacervate formation above Tt decreases it. (c) 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012