pharma-congress-molecular-medicine-2018-posters

Page 48

O c t o b e r 1 9 - 2 0 , 2 0 1 8 | T o k y o , J a p a n

Pharma Congress 2018 & Molecular Medicine 2018

& Psychiatric Disorders 2018

Asian Journal of Biomedical and Pharmaceutical Sciences

ISSN: 2249-622X

Volume 8

International Conference on

PHARMACEUTICS AND NOVEL DRUG DELIVERY SYSTEMS

International Conference on

CELLULAR AND MOLECULAR MEDICINE

Annual Congress on

PSYCHIATRY AND PSYCHIATRIC DISORDERS

OF EXCELLENCE

IN INTERNATIONAL

MEETINGS

YEARS

Asian J Biomed Pharmaceut Sci 2018, Volume 8 | DOI: 10.4066/2249-622X-C3-009

NOVEL PROPERTIES OF INDIVIDUAL MYOSIN HEADS IN SKELETAL

MUSCLE AS REVEALED BY EXPERIMENTS USING THE GAS

ENVIRONMENTAL CHAMBER

Haruo Sugi

Teikyo University Medical School, Japan

lthough it is generally believed that muscle contraction results from ATP-driven cyclic attachment and detachment between

myosin heads extending from myosin filaments and corresponding myosin-binding sites on actin filaments, the movement

of myosin heads remains to be a matter for debate and speculation. The most straightforward way to visualize and record indi-

vidual myosin head movement coupled with ATP hydrolysis is to use the carbon film-sealed gas environmental chamber (EC),

which enables us to keep biological specimens like muscle actin and myosin filaments in wet, living state in the high vacuum

of a transmission electron microscope. We have succeeded in recording ATP-induced movement of individual myosin heads,

position-marked with gold particles (diameter, 20 nm) via site-directed antibodies to myosin head, and found novel properties

of individual myosin heads, which are summarized as follows: In the absence of ATP, myosin heads take stable neutral position,

around which they fluctuate. In the absence of actin filaments, individual myosin heads move away from, but not towards the

bare region at the center of myosin filaments, i.e. they perform recovery stroke. After exhaustion of applied ATP return to their

neutral position. The above finding indicates that myosin heads can sense the absence or presence of actin filament to determine

their direction of ATP-induced movement, without being guided by actin filaments. In the presence of actin filaments, individual

myosin heads perform power stroke in two different modes depending on experimental conditions. We emphasize that our EC

experiment is the only method to visualize and record ATP-coupled movement of individual myosin heads, while all other meth-

ods can only obtain ambiguous results due to asynchronous nature of myosin head movement.