Abstract: Methods for improving purification and quantification of platelet derived growth factor (PDGF) proteins having structural heterogeneity are provided. Preparation of substantially pure isoforms of these proteins is achieved using TSK sulfopropyl cation exchange chromatography and reverse phase high performance liquid chromatography. A reverse charged capillary zone electrophoresis method enables quantification of substantially pure isoforms of these proteins resulting from endoproteolytic post-translational modifications. Compositions of the invention are substantially purified isoforms of secreted PDGF proteins having structural heterogeneity, more particularly purified intact, single-clipped, and double-clipped isoforms of recombinant PDGF-BB. Pharmaceutical compositions comprising at least one of these substantially purified recombinant PDGF isoforms and methods for their use in promoting wound healing are also provided.

Abstract: Compositions and methods for expression of heterologous mammalian proteins and their secretion in the biologically active mature form using a yeast host cell as the expression system are provided. Compositions of the invention are nucleotide sequences encoding a signal peptide sequence for a yeast secreted protein, an optional leader peptide sequence for a yeast secreted protein, a native propeptide leader sequence for a mature protein of interest, and a sequence for the mature protein of interest, all operably linked to a yeast promoter. Each of these elements is associated with a processing site recognized in vivo by a yeast proteolytic enzyme. Any or all of these processing sites may be a preferred processing site that has been modified or synthetically derived for more efficient cleavage in vivo. The compositions are useful in methods for expression of heterologous mammalian proteins and their secretion in the biologically active mature form.