TABLE 5.

Penetration depth of the NBD group in membrane-bound NBD-melittin analogs by the parallax method

	Distance from the center of the bilayer, zcF (Å)*
Membrane	N-ter	Lys-7	Trp-19
DOPC	17.9 ± 0.3	19.4 ± 0.6	10.6‡
DOPC/60%DOPG	19.2 ± 0.5	20.9 ± 0.7	10.3‡
DOPC/20% chol†	20.1 ± 0.6	18.8 ± 0.7	17.4§

^*Depths were calculated from fluorescence quenchings obtained with samples containing 10 mol % of Tempo-PC and 5-PC and using Eq. 8. Samples were excited at 465 nm, and emission was collected at 530 nm. The depth values represent mean ± SE of at least three independent measurements. The ratio of melittin/total lipid was 1:100 (mol/mol) and the concentration of melittin was 1.07 μM in all cases. See Materials and Methods for other details.

^†Corrections were made for the altered concentrations of spin-labeled lipids (for lateral distribution) and the depths of the quenchers used in membranes containing cholesterol (64).

^‡From Ghosh et al. (9).

^§From Raghuraman and Chattopadhyay (10).