[OPTICAL REVIEW Vol. 6, No. 1 (1999) 16-23]

Simultaneous Measurement of Individual ATPase and Mechanical Reactions by a Single Myosin Molecule at Work*

Akihiko ISHIJIMA,1 Hiroaki KOJIMA,2 Hiroto TANAKA3 and Toshio YANAGIDA3,4

1Department of Applied Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 Japan, 2Kansai Advanced Research Center Communications Research Laboratory, 588-2, Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, Hyogo, 651-2401 Japan, 3Single Molecule Processes Project, ICORP, JST, 2-4-14, Senba-higashi, Mino, Osaka, 562-0035 Japan and 4Department of Physiology, Osaka University Medical School, Suita, Osaka, 565-0871 Japan

(Received September 20, 1998; Accepted October 29, 1998)

Based on techniques for single molecule imaging and nanomanipulation by optical tweezers, we have developed a new technique that allows simultaneous measurement of individual ATPase and mechanical reactions from a single myosin molecule during force generation. We show how the ATPase reaction couples to the mechanical reaction directly at the single molecule level. The results show that the myosin head can produce force even after releasing the bound nucleotide, probably ADP, suggesting that the chemical energy driven by ATP hydrolysis can be hysteretically stored in the myosin molecule. This view does not support a widely accepted hypothesis in which the force generation is tightly coupled to ligand dissociation.

Key words : optical tweezers, evanescent field, nano-manipulation, actin, myosin, molecular motor