![Figure 6. CD spectroscopy reveals Ca2+-dependent conformational changes in the WT-RCK1 domain. (A) Far-UV CD spectra of the BKCa WT-RCK1 domain obtained in increasing free [Ca2+]. The spectra exhibit decreased overall amplitude with increasing [Ca2+], and a red shift in the ellipticity minimum from 220 to 223 nm, indicating Ca2+-dependent structural alterations. (B) Estimated secondary structure fractions of WT-RCK1 as a function of free [Ca2+]. The α-helix and β-sheet fraction data obtained at different [Ca2+] are fitted to a Hill function. (C and D) As in A and B, respectively, for purified D362/367A-RCK1. The double mutant exhibits little change in secondary structure up to 35 µM of free [Ca2+].](https://cdn.rupress.org/rup/content_public/journal/jgp/136/2/10.1085_jgp.200910374/5/jgp_200910374_rgb_fig6.jpeg?Expires=1767665991&Signature=QYjoAzE~HHUdyIxAMMlE70VF9rPuozEyc8jRxfROWJeJldEueswN4-kv871J0bX-PEzPv6XUfeLXeJztcxqFpWq9py43LXpZgnSPESJK43bL6RZwRvJ0-RC6XM3xnjuyNDbrE6cxQbthlcq45a7wBiMFPVai8eaqAG0I2pCCcO0WbMSHJ23WzWep1AAmeHGA6bmZ~IId~-IGhzabMt4ZZJym7SgCINVMxvYDfgzDSiYw1GyU4q1Du4m0Dp-HRyQr90gv3CrHGSA~5nFdv4FZbrUH~goOrbabZJdmtpR3Y2pWkE5ee0BY8ovY338EelQiLNTGnE9sK8YuVeKtRS8xew__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Figure 6.
CD spectroscopy reveals Ca2+-dependent conformational changes in the WT-RCK1 domain. (A) Far-UV CD spectra of the BKCa WT-RCK1 domain obtained in increasing free [Ca2+]. The spectra exhibit decreased overall amplitude with increasing [Ca2+], and a red shift in the ellipticity minimum from 220 to 223 nm, indicating Ca2+-dependent structural alterations. (B) Estimated secondary structure fractions of WT-RCK1 as a function of free [Ca2+]. The α-helix and β-sheet fraction data obtained at different [Ca2+] are fitted to a Hill function. (C and D) As in A and B, respectively, for purified D362/367A-RCK1. The double mutant exhibits little change in secondary structure up to 35 µM of free [Ca2+].
