Structural analysis and molecular modeling of the RvH2-e functional unit of Rapana venosa hemocyanin

Rapana venosa hemocyanin (RvH), a circulating glycoprotein of the marine snail, has a complex structure. To provide details on the stability of the protein, one functional unit, RvH2-e, was compared with the native molecule and the structural subunits, RvH1 and RvH2, via pH–T diagrams, typical phase portraits for stability and denaturation reversibility. By analyzing the T transition curves of RvH2-e at different pH values, several parameters of the thermodynamic functions were obtained. Increasing the temperature from 25 °C to 55 °C, the reversibility of the molecule of protein also increases, opening a reversibility window within the range of pH 4.0–8.0. On analyzing the pH transition curves, the start of the acid denaturation (below pH 6) and alkaline denaturation (above pH 9) was determined to be between 20 °C and 35 °C. For this range, the thermodynamic functions ΔH° and ΔG° for a standard temperature of 25 °C were calculated.

Research Highlights
► Properties and stability of one functional unit of Rapana venosa HC.
► Analyzing the T transition curves of RvH2-e at different pH values.
► Analyzing the pH transition curves.
► Calculation of the thermodynamic functions ΔH° and ΔG° for a standard temperature of 25 °C.
► New large sets of pH–T data characterizing the conformational stability of RvH2-e.