Expression and purification of goat lactoferrin from Pichia pastoris expression system

The recombinant goat lactoferrin (rGLF) was expressed in the methylotropic yeast Pichia pastoris using pGAPZ alpha C vector, GAP as promotor, and Zeocin as the selective marker. After transformation of the GLF-pGAPZ alpha C into Pichia pastoris X-33 expression host, the GLF-pGAPZ alpha C vector was integrated into the GAP promotor locus of Pichia pastoris is X-33 chromosome. The rGLF was expressed and secreted into the broth using alpha-factor preprosequence. SDS-PAGE and PAS staining analysis indicated that the rGLF could be purified to electrophoretic homogeneity by heparin-Sepharose 6 Fast Flow affinity chromatography and glycosylated by the expression host. The yield of purified rGLF was approximately 2.0 mg/L of culture broth. The N-terminal sequence was identical to the native goat lactoferrin (nGLF). The iron-binding bahavior, papin-inhibiting property, and thermal stability of the purified rGLF were comparable to nGLF. This is the 1st report of intact got lactoferrin expression using the P. pastoris system.