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The attachment/detachment process of lysozyme molecules on a monoclinic lysozyme crystal surface studied by single-molecule visualization

Guoliang Dai 1Gen Sazaki 2

1. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
2. Institute of Low Temperature Science, Hokkaido University (ILTS), N19-W8, Kita-ku, Sapporo 060-0819, Japan

Abstract

Attachment/detachment process of protein molecules on a crystal surface is one of the key elementary processes of protein crystal growth. In particular, how the attachment/detachment process happens and changes during crystallization process is still unclear. In this work, we conducted, by single-molecule visualization, the observation of fluorescent-labeled lysozyme molecules on {10-1} faces of a seed monoclinic lysozyme crystals under an almost equilibrium condition and a growth condition. We measured the changes in number density of florescent-labeled lysozyme molecules (whose positions were not changed, within an accuracy of one pixel size, for longer than a certain residence time) as a function of an adsorption time. We found that there was an induction period (~120 min) of the attachment/detachment process, during which period the number density remained constant, under both equilibrium and growth condition. After the "induction period", number density of florescent-labeled lysozyme molecules increased linearly with the adsorption time. Supersaturation significantly changes the attachment/detachment process: the increase in supersaturation obviously increases the adsorption (attachment) rate and decreased the induction period. We analyzed the changes in the ratio of adsorbed florescent-labeled lysozyme molecules (whose residence time was longer than 20 min) on steps of a seed crystal. The results showed that the induction period is an important factor affecting the adsorption position of molecules under equilibrium condition. Moreover, we tracked the changes of position of one labeled lysozyme molecule absorbed on steps under the growth condition. We found experimentally that the adsorbed molecule moved along a step under a low supersaturation condition.

 

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Related papers

Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 3, by Guoliang Dai
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-10 10:01
Revised:   2013-04-10 10:01