Occult symptomatic bilateral pure Leydig cell tumors in a postmenopausal woman: a case report.

Background: Pure Leydig cell tumors (LCTs) represent 0.1% of ovarian masses. Postmenopausal patients typically present with virilization.

Local Backbone Flexibility as a Determinant of the Apparent pK Values of Buried Ionizable Groups in Proteins.

Ionizable groups buried in the hydrophobic interior of proteins are essential for energy transduction. These groups can have highly anomalous pK values that reflect the incompatibility between charges and dehydrated environments. A systematic study of pK values of buried ionizable groups in staphylococcal nuclease (SNase) suggests that these pK values are determined in part by conformational reorganization of the protein.