Abstract
AntiFreeze Proteins (=AFPs) bind to a surface of ice crystals and inhibit their growth. Some living
organisms; fishes, insects and fungus, at low-temperature environment have several different types
of AFPs. AFPs protect their body from freezing damages. To clarify the antifreeze effect of lpAFP
(isolated from longsnout poacher, a fish living in the sea of Okhotsk) at single molecular level, we
performed dynamical observations by using diffracted X-ray tracking (=DXT). DXT is the method
to observe single molecular motions using X-rays and gold nanocrystals as probe. Gold
nanocrystals were labeled on the target proteins, and when irradiated with X-rays, we monitored
diffracted spots from gold nanocrystals. We can observe motions of the proteins by tracking these
x-ray diffraction spots. In this study, we used lpAFP isolated from longsnout poacher, and observed
the temperature dependency of the lpAFP’s single molecular Brownian motion.
