Suppose that the thiol group of a particular Cys residue is buried in the interior of the three-dimensional structure of a particular protein, and the environment in the interior is hydrophobic. Would the pKa of the buried Cys thiol group be higher than, lower than, or the same as the pKa of a Cys thiol group on the surface of the protein (exposed to the surrounding H2O)? Briefly justify your answer.