The synthetic nanomachine powered by bovine cardiac myosin demostrates that force and power of the atrial myosin isoform are less then those of the ventricular isoform

Abstract

The functional differences of the α- and β-cardiac myosin that make up the atrial and ventricular chambers of the human heart have been described in detail with solution kinetic analysis, showing that α-cardiac myosin has faster ATP hydrolysis and faster ADP release so that the ATPase cycle time is ten times shorter, but the duty ratio (r) is similar to that of β-cardiac myosin. Instead, the isoform-dependence of mechanical performances remains elusive as the force of the β-cardiac myosin was found either twice higher (attributed to a larger r) with in vitro mechanics or similar in Ca2+-activated skinned myocytes.