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SOLUTION STRUCTURE OF TERTIAPIN DETERMINED USING NUCLEAR MAGNETIC RESONANCE AND DISTANCE GEOMETRY
Structural highlights
FunctionTERT_APIME Presynaptic neurotoxin that blocks the inwardly rectifying Kir1.1/KCNJ1 and Kir3.1/3.4 (KCNJ3/KCNJ5) potassium channels with high affinity by binding to the M1-M2 linker region of these channels in a 1:1 stoichiometry. It may block the potassium channel pore by occluding its alpha helix into the channel vestibule. Tertiapin-Q also inhibits calcium-activated large conductance BK-type (KCNMA) potassium channels in a concentration-, and voltage-dependent manner, in addition to inhibiting Kir3.1/3.2 (KCNJ3/KCNJ6) heteromultimers potassium channels. It can prevent dose-dependently acetylcholine(ACh)-induced atrioventricular blocks in mammalian hearts, as KCNJ3/KCNJ5 channels (also named I(KACh), because these channels are activated by ACh) are found in mammalian myocytes. Interacts specifically with calmodulin in the presence of calcium.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedThe solution structure of tertiapin, a 21-residue bee venom peptide, has been characterized by circular dichroism (CD), two-dimensional nuclear magnetic resonance (NMR) spectroscopy, and distance geometry. A total of 21 lowest error structures were obtained from distance geometry calculations. Superimposition of these structures shows that the backbone of tertiapin is very well defined. One type-I reverse turn from residue 4 to 7 and an alpha-helix from residue 12 to 19 exist in the structure of tertiapin. The alpha-helical region is best defined from both conformational analysis and structural superimposition. The overall three-dimensional structure of tertiapin is highly compact resulting from side chain interactions. The structural information obtained from CD and NMR are compared for both tertiapin and apamin (ref. 3), another bee venom peptide. Tertiapin and apamin have some similar secondary structure, but display different tertiary structures. Solution structure of tertiapin determined using nuclear magnetic resonance and distance geometry.,Xu X, Nelson JW Proteins. 1993 Oct;17(2):124-37. PMID:8265561[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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