Purpureotin: a novel di-dimeric C-type lectin-like protein from Trimeresurus purpureomaculatus venom is stabilized by noncovalent interactions |
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Authors: | Li Xiaolei Zheng Lu Kong Chunguang Kolatkar Prasanna R Chung Maxey C M |
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Affiliation: | Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. |
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Abstract: | Purpureotin, a novel di-dimeric C-type lectin-like protein (CLP) from Trimeresurus purpureomaculatus, was purified and sequenced. While its native molecular mass was determined to be 63kDa, purpureotin showed a single band of 30kDa on nonreducing SDS-PAGE and two polypeptide chains (16.0 and 14.5kDa) under reducing condition. These results were subsequently confirmed by mass spectrometric analyses. Based on these results, we postulate that purpureotin is a dimer of the alpha,beta-heterodimer which is held together by noncovalent interactions. Molecular modeling studies indicate that a dimer of alpha,beta-heterodimers can be formed where the alpha chains are held together by electrostatic charges and beta chains via hydrophobic interactions. Functionally, purpureotin induced platelet aggregation without any cofactor in a dose-dependent manner. However, the platelet aggregation effect was blocked by echicetin. Therefore, purpureotin is assumed to be a GPIb-binding protein which binds to the same or a closely related GPIb site on platelets as echicetin. |
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Keywords: | C-type lectin-like protein Purpureotin Trimeresurus purpureomaculatus Platelet aggregation Sequence identity Molecular modeling |
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