(a) Rotational correlation time τ|| of 0.2 mM TEMPO-stearate in 100 mM phospholipid vesicles in Hepes buffer at pH 7.4 as a function of temperature. Symbols used to identify the different lysophospholipid-phospholipid concentrations in mixed DMPG-LMPC vesicles are: (○) 20 mM LMPC, 80 mM DMPG; (□) 10 mM LMPC, 90 mM DMPG; (◇) 5 mM LMPC, 95 mM DMPG; (△) 4 mM LMPC, 96 mM DMPG; (▽) 3.5 mM LMPC, 96.5 mM DMPG; (▷) 2 mM LMPC, 98 mM DMPG; (●) 100 mM DMPG (DMPG vesicles) and (■) 100 mM LMPC (LMPC micelles). Error bars are standard deviations of five measurements. Lines are to guide the eyes.