A surgical instrument and actuation mechanism comprises an end effector, the end effector including opposing faces, and a positioning slot. The positioning slot includes a linear portion and a radial portion. In accordance with one aspect, the surgical instrument further comprises an actuation mechanism engaged with the positioning slot, wherein the opposing faces of the end effector move in a parallel manner when the actuation mechanism moves within the linear portion of the positioning slot, and wherein the opposing faces of the end effector move in an angular manner when the actuation mechanism moves within the radial portion of the positioning slot.