Related Experiment Video

Updated: Jul 14, 2026

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
10:52

Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex

Published on: July 27, 2022

Antiamoebin I in methanol solution: rapid exchange between right-handed and left-handed 3(10)-helical conformations

Zakhar O Shenkarev1, Alexander S Paramonov, Kirill D Nadezhdin

  • 1Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.

Chemistry & Biodiversity
|June 26, 2007
PubMed

Insights

Antiamoebin I (Aam-I), a fungal antibiotic, exhibits dynamic conformational flexibility in solution. This molecular motion, particularly hinge-bending around Aib(8), influences its membrane binding and channel formation, explaining its lower biological activity compared to similar peptaibols.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biophysics

Background:

  • Antiamoebin I (Aam-I) is a membrane-active peptaibol antibiotic derived from fungi.
  • Peptabols are known for their diverse biological activities, often related to membrane interactions.

Purpose of the Study:

  • To elucidate the solution structure and dynamics of Antiamoebin I.
  • To correlate conformational flexibility with the antibiotic's functional and biological activity.

Main Methods:

  • Utilized uniformly (13)C,(15)N-labeled Antiamoebin I for Nuclear Magnetic Resonance (NMR) spectroscopy, including J couplings and (15)N-relaxation measurements.
  • Employed Circular Dichroism (CD) spectroscopy and molecular modeling with Monte Carlo simulations.

Main Results:

  • Identified fast exchange between right-handed and left-handed 3(10)-helical conformations in the N-terminal region (Phe(1)-Gly(6)) of Aam-I in methanol.
  • Detected an additional conformational exchange process at the Aib(8) residue, coupled with hinge-bending motions.
  • Confirmed findings through (15)N-NMR relaxation and CD spectroscopy.

Conclusions:

  • The high dynamic flexibility of Antiamoebin I, driven by conformational exchange and hinge-bending, likely hinders effective membrane binding and ionic channel formation.
  • This dynamic 'propensity' explains the relatively lower activity of Aam-I compared to other peptaibols like zervamicin.

More Related Videos

Millisecond Hydrogen/Deuterium-Exchange Mass Spectrometry for the Study of Alpha-Synuclein Structural Dynamics Under Physiological Conditions08:40

Millisecond Hydrogen/Deuterium-Exchange Mass Spectrometry for the Study of Alpha-Synuclein Structural Dynamics Under Physiological Conditions

Published on: June 23, 2022

Investigating Receptor-ligand Systems of the Cellulosome with AFM-based Single-molecule Force Spectroscopy11:34

Investigating Receptor-ligand Systems of the Cellulosome with AFM-based Single-molecule Force Spectroscopy

Published on: December 20, 2013

Related Concept Videos

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution00:52

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons00:58

¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons

Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called prochiral or enantiotopic and are related by a mirror plane. Enantiotopic protons are chemically equivalent in an achiral environment. Because most proton NMR spectra are recorded using achiral solvents, enantiotopic hydrogens yield a single signal.
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
Properties of Enantiomers and Optical Activity02:24

Properties of Enantiomers and Optical Activity

It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
Naming Enantiomers02:21

Naming Enantiomers

The naming of enantiomers employs the Cahn–Ingold–Prelog rules that involve assigning priorities to different substituent groups at a chiral center. Each enantiomer, being a distinct molecule, is assigned a unique name by the Cahn–Ingold–Prelog (CIP) rules, also called the R–S system. The prefix R- or S- attached to the chiral centers in an enantiomer is dependent on the spatial arrangement of the four substituents on the chiral center. The R–S system essentially comprises three steps:...
Prochirality02:05

Prochirality

The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
Newman Projections02:06

Newman Projections

Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.