Multifunctional molecular weight protein ladders and methods of making thereof are disclosed herein that are useful for determining the molecular weight of a test protein and/or the relative mass or amount of the test protein in a protein separation assay, such as gel electrophoresis or western blotting. Also included are compounds of Formula I (e.g., mono acetylated MP-11 NHS ester) that may be used to label purified proteins of the protein ladder. The MP-11 label protein ladder can be detected on a blotting membrane by exposing the microperoxidase to a suitable substrate, such as a chromogenic substrate or a chemiluminescent substrate.