Phenylalanyl and tyrosyl side chain mobility in the M13 coat protein reconstituted in phospholipid vesicles

The authors studied the behavior of the major coat protein of the filamentous coliphage, M13, when reconstituted into vesicles consisting of 80% dimyristoyl-phosphatidylcholine, 10% cardiolipin, and 10% dipalmitoylphosphatidic acid, by weight. The protein had been labeled, in vivo, with 3-fluoro analogues of phenylalanine and tyrosine, thus providing specific labels of the hydrophilic and hydrophobic regions of the protein, respectively, for study using super(19)F NMR (nuclear magnetic resonance). To determine the exposure and orientation of the vesicle-bound coat protein, chymotryptic digestion and temperature experiments were done. Chymotryptic digestion, monitored by super(19)F NMR and paper electrophoresis, showed that the protein was incorporated symmetrically.