Structural analysis and disulfide-bridge pairing of two odorant-binding proteins from Bombyx mori

Pheromone-binding protein (PBP) and general odorant-binding proteins (GOBPs ) were purified from the antennae of Bombyx mori and structurally character ised, The amino acid sequence of GOBP-8 has been corrected. The disulphide arrangements of PBP and GOBP-8 have been determined by a combined mass spec trometric/Edman degradation approach. The same cysteine pairings, Cys19-Cys 54, Cys50-Cys108, and Cys97-Cys117, were found in both proteins, suggesting that such patterns occur commonly throughout this family of molecules. Thi s arrangement of disulphide bonds indicates that the three-dimensional stru cture of insect OBPs is defined by three loops, rich in helical content, wh ich can vary in size and charge distribution from one protein to another. ( C) 1999 Academic Press.