Supplementary data for HIV - 1 Tat membrane interaction probed using X - ray and neutron scattering , CD , and MD simulations

As hydration proceeded, the mosaic spread, or degree of misorientation, increased. This was apparent by the increasing lengths of the arcs emanating out from the h=1 and h=2 lamellar orders, shown in Fig. S1. Mosaic spread was determined by examining lamellar orders in the LAXS CCD position. Matlab was used to plot the intensity of a lamellar order as a function of η, the angle off the meridian. The intensity data above and below the lamellar order were averaged and subtracted from the intensity at the lamellar order to remove diffuse scattering. The subtracted data were fit with a Voigtian function, setting the Gaussian width to the beam width, and extracting the Lorentzian width (ωL). Then, the following equation was applied to obtain α, ωL 2 = α 2 + 4(γ θB) 2 , where γ=angle of incidence and θB is half the scattering angle of the lamellar order. These results are included in Fig. S2, as a function of time after stopping the helium flow and beginning the hydration. The cooling Peltier was at first set to 200 mAmps, which caused the lamellar D-spacing to increase. It was then decreased to 100 mAmps, which caused less water to condense into the sample, and the lamellar D-spacing decreased, as did the mosaic spread. Thus, Tat’s ability to disrupt the bilayers appears to be a reversible effect, dependent on the hydration of the sample.