Calponin is a thin filament-associated smooth muscle protein that has been suggested to
play a role in the regulation of smooth muscle contraction. We have used circular dichroism
spectroscopy, electron microscopy, and analytical ultracentrifugation to study the physical
properties of recombinant chicken gizzard α-calponin. The α-helix content of α-calponin was
estimated from its circular dichroism spectrum to be~ 13%. α-Calponin melts with a single
sharp transition at~ 57° C. Rotary shadowing electron micrographs of α-calponin reveal …