Thermal melt analysis of tail fragments. Thermal melt analysis shows all tail fragments, except R1165C, have stability similar to that of wild type. The melting temperature for each tail fragment was determined by CD monitoring at 222 nm as the temperature was raised from 10°C to 80°C. Shown are the data points for each tail fragment along with the curve used to calculate the melting temperature. Mean residue ellipticity (degrees cm² dmol^–1) was plotted versus temperature (x-axis), and a best-fit equation was generated. The midpoint of the transition was then determined by this equation, and a vertical dashed line was added.