O-Propargyl-Puromycin (OP-puro) is a potent protein synthesis inhibitor, a puromycin acetylene analog.

O-Propargyl-Puromycin can be used to image and affinity purify nascent proteins in cells and animals. O-Propargyl-Puromycin inhibits protein synthesis in reticulocyte lysates and cultured cells with two to three times less potency than unmodified puromycin. O-Propargyl-Puromycin forms covalent conjugates with nascent polypeptide chains that are rapidly turned over by the proteasome and can be visualized or trapped by copper(I)-catalyzed azide-alkyne cycloaddition reactions.[1]

Tissue from uninjected mice showed low nonspecific staining, whereas tissue from O-Propargyl-Puromycin-injected mice showed a specific pattern of O-Propargyl-Puromycin incorporation into nascent proteins. In the small intestine, cells in the crypts and at the base of intestinal villi have the greatest translation capacity, consistent with the high proliferative and secretory activity of these cells. Staining was particularly intense in Paneth cells, which are located near the base of the crypts and are filled with secretory vesicles. Intense O-Propargyl-Puromycin labeling of vesicles in Paneth cells suggests that prematurely terminated O-Propargyl-Puromycin-conjugated secretory proteins translocate into the endoplasmic reticulum (ER) lumen.[1]