Phosphatidylgly cerols

The positively charged amino acids promote the interaction between the peptide and the negatively charged head groups of the phosphatidylgly-cerol (123-125). The purpose of this particular property has been proposed to facilitate the transition of surfactant phospholipid membranes from the lamellar body to the alveolar spaces (123). 

Fig. 7. The increase in surface pressure of phospholipid monolayers as a function of signal-peptide concentration for the various E. coli LamB synthetic signal sequences (from Briggs, 1986). A monolayer of egg phosphatidylethanolamine and egg phosphatidylgly-cerol (65 35) was spread from a benzene solution onto 5 mM Tris buffer, pH 7.3, yielding a hnal surface pressure of 20 dyn/cm after evaporation of the benzene. The peptide was added by injecting a concentrated solution below the lipid-water interface. The surface pressure was measured by the du Noiiy ring method with a Fisher Autotensiomat equipped with a platinum-iridium ring. The plateau values are plotted as a function of the peptide concentration for the wild-type (O), Pro— Leu pseudorevertant (A), and deletion-mutant ( ) peptides.

Fig. 2.4. Densitometer traces of powder X-ray diffraction intensities from fully-hydrated dipalmitoyl phosphatidylgly-cerol multibilayers at pH 8.0 (1.5 M KCl/50 mM Tris) and pH 1.5 (1.5 M KCl/HCl), at 20°C. (a) Low-angle, and (b) high-angle reflection regions, respectively. The diffraction intensity is plotted against the diffraction angle 20 and the corresponding Bragg spacings (Watts et al., 1981).

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