NMR study of the antifreeze activities of active and inactive isoforms of a type III antifreeze protein

摘要

Thequaternary‐amino‐ethyl1(QAE1)isoformsoftypeIIIantifreezeproteins(AFPs)preventthegrowthoficecrystalswithinorganismslivinginpolarregions.Wedeterminedtheantifreezeactivityofwild‐typeandmutantconstructsoftheJapanesenotched‐fineelpout(ZoarceselongatesKner)AFP8(nfeAFP8)andcharacterizedthestructuralanddynamicspropertiesoftheirice‐bindingsurfaceusingNMR.WefoundthatthethreeconstructscontainingtheV20Gmutationwereincapableofstoppingthegrowthoficecrystalsandexhibitedstructuralchanges,aswellasincreasedconformationalflexibility,inthefirst310helix(residues18–22)ofthesequence.OurresultssuggestthattheinactivenfeAFP8sareincapableofanchoringwatermoleculesduetotheunusualandflexiblebackboneconformationoftheirprimaryprismplane‐bindingsurface...