FIGURE 5.

Neutron reflectivity with H₂O as the subphase instead of D₂O. (A) Neutron reflectivity of the monolayer, monolayer with bound CTB₅, and monolayer with bound CTAB₅. Solid and dashed lines indicate the fit corresponding to the profile in B. Points with error bars correspond to measured data. (B) Scattering length density profile of fits shown in A obtained by box model fitting methods. The same features of lipid tails, lipid heads, and the B₅ subunit can be seen. The A-unit of CTAB₅ is not very visible due to small contrast between the scattering length density of H₂O and the A-unit layer. These results are consistent with that of NR done on D₂O. The difference in β(z) of the lipid tail region for bound CTAB₅ and CTB₅ is most likely due to different protein coverage. The increased amount on CTB₅ coverage (indicated by a larger β(z) for Box 4) is responsible for a larger decrease in lipid tail β(z) due to a larger increase in area per molecule of the lipid layer.