Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of bovine pancreatic and pecan xylem RNase A. (A) Bovine pancreatic RNase A. Approximately 200 μg of protein was loaded. STD: Standard (loaded: 12 μl). Numbers in the left and right columns of the figure indicate molecular mass. (B) Purified pecan urease. The 14-kDa enzyme has been purified to homogeneity. Numbers in the left column and right side of the figure indicate molecular mass in kDa. The migration distance on the SDS-PAGE gel indicates the size of protein. Std = Protein Standards.