title: Purpureotin: a novel di-dimeric C-type lectin-like protein from Trimeresurus purpureomaculatus venom is stabilized by noncovalent interactions.
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.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Li
authors.forename: Lu
authors.initials: L
authors.lastname: Zheng
authors.forename: Chunguang
authors.initials: C
authors.lastname: Kong
authors.forename: Prasanna R
authors.initials: PR
authors.lastname: Kolatkar
authors.forename: Maxey C M
authors.initials: MC
authors.lastname: Chung
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003435:Crotalid Venoms / Q000737:chemistry*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004355:Drug Stability; D037181:Lectins, C-Type / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010974:Platelet Aggregation / Q000187:drug effects; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics; D011506:Proteins / Q000737:chemistry* / Q000235:genetics* / Q000494:pharmacology; D011817:Rabbits; D020539:Sequence Analysis, Protein; D021241:Spectrometry, Mass, Electrospray Ionization; D017841:Trimeresurus / Q000378:metabolism*; D014757:Viper Venoms / Q000737:chemistry
chemical_list: D003435:Crotalid Venoms; D037181:Lectins, C-Type; D021122:Protein Subunits; D011506:Proteins; D014757:Viper Venoms