The photochemical activities of phycoerythrocyanin alpha-subunits from
Mastigocladus laminosus separated by isoelectric focusing were tested
by irradiating at 500, 550, 577 and 600 nm. Two types of photoreversi
ble photochromic responses have been characterized by absorption and a
bsorption difference spectroscopy. Type I is the well-known absorption
shift from 571 to 506 nm. Type II is a new response characterized by
a line-broadening of the 570 nm absorption.