Figure 3
From: Chemistry of conjugation to gold nanoparticles affects G-protein activity differently
Effect of AuNP conjugation on Gα i1 basal nucleotide exchange rates. (A) Displays effect of non-covalent interaction between AuNP and Gαi1 on basal GTPγS uptake by Gαi1-GDP. Solid line represents 0 nM AuNP (only Gαi1); Dotted line represents 0.1 nM AuNP; Dash-dot-dot line represents 0.2 nM AuNP. (B) Shows effect of N-terminal covalent conjugation of Gαi1 to AuNP. Solid line represents 0 nM AuNP (only Gαi1); Dotted line represents covalently conjugated AuNP- Gαi1. All the experiments were performed with final concentration of 200 nM Gαi1 (unconjugated or conjugated) in a quartz cuvette containing 5 mM Hepes-Na (pH 8.0), 10 mM NaCl, 0.5 mM MgCl2, 1 μM GDP. Relative tryptophan emission at 340 nm was monitored by exciting the sample at 295 nm with continuous stirring after addition of GTPγS to a final concentration of 3.2 μM. Non-covalently conjugated AuNP- Gαi1 displayed deaccelerated rates of basal GTPγS uptake (fold decrease in apparent rates upto 0.8). N-terminal covalent conjugation displayed ~ 5 fold fast basal GTPγS uptake.