Analysis of local structure of Arg10 domain in apo-α-lactalbumin with a polarity-sensitive arginine-specific fluorescent probe

Abstract

The polarity-sensitive fluorescent probe, 3-(4-chloro-6-p-glyoxalphenoxy-1,3,5-triazinylamino)-7-(dimethylamino)-2-methylphenazine, was used to analyze the local structure of apo-α-lactalbumin by detecting the polarity and conformational changes of the arginine residue (Arg10) domain. The polarity of the Arg10 domain in both native and heat-denatured apo-α-lactalbumin was determined, which corresponds to a dielectric constant of 16, and the hydrophobic core near the Arg10 was found to be conservative for heating. Meanwhile, the effect of Ca2+ binding on the conformational changes of the Arg10 domain was studied, revealing that the hydrophobic core near the Arg10 is insensitive to the binding of Ca2+.