Related Experiment Video
Updated: Aug 11, 2026
16:57
MALDI Imaging Mass Spectrometry of Neuropeptides in Parkinson's Disease
Published on: February 14, 2012
Conformational changes in beta-endorphin as studied by electrospray ionization mass spectrometry
Rapid Communications in Mass Spectrometry : RCM
|December 18, 2001
Summary
Beta-endorphin (BE) adopts a compact structure in methanol, transitioning from a random coil in water. Hydrogen/deuterium exchange reveals 61% alpha-helix formation in mixed solvents, indicating significant conformational changes.
Area of Science:
- Biochemistry
- Structural Biology
- Mass Spectrometry
Background:
- Beta-endorphin (BE) is a crucial endogenous opioid peptide with diverse physiological roles.
- Understanding BE's structure is vital for elucidating its function and developing therapeutic strategies.
- Conformational flexibility of peptides influences their biological activity.
Purpose of the Study:
- To investigate the conformational changes of beta-endorphin (BE) induced by methanol.
- To characterize the structural transition of BE in varying methanol concentrations.
- To determine the secondary structure content of BE in mixed aqueous-organic solvents.
Main Methods:
- Electrospray ionization-mass spectrometry (ESI-MS) was employed to study BE structure.
- Charge-state distribution (CSD) analysis was used to monitor conformational changes.
- Time-resolved hydrogen/deuterium (H/D) exchange experiments were performed using ESI-MS.
Main Results:
- BE exhibits a random coil, open structure in aqueous solutions.
- Increasing methanol concentration leads to a more compact conformation of BE.
- H/D exchange data indicate the formation of approximately 61% alpha-helix structure in mixed solvents.
Conclusions:
- Methanol induces significant conformational changes in beta-endorphin.
- BE transitions from an unfolded state to a more structured conformation in the presence of methanol.
- The formation of alpha-helical structure is a key feature of BE's compacted state in mixed solvents.
More Related Videos
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
05:45Capillary Electrophoresis-based Hydrogen/Deuterium Exchange for Conformational Characterization of Proteins with Top-down Mass Spectrometry
Published on: June 8, 2021
Related Concept Videos
00:52¹H 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...
01:12Electrospray Ionization (ESI) Mass Spectrometry
Higher molecular weight biomolecules are nonvolatile compounds that may decompose before ionizing or vaporizing during mass analysis with conventional electron impact ionization methods. Accordingly, electrospray ionization (ESI) is the favored method for vaporizing and ionizing biomolecules as it circumvents rapid fragmentation and enables the recording of mass signals for the entire biomolecule.
ESI utilizes electrical energy to transfer ions from the liquid phase of the sample into the...
ESI utilizes electrical energy to transfer ions from the liquid phase of the sample into the...
01:15High-Resolution Mass Spectrometry (HRMS)
The resolution of a mass spectrometer depends on the efficiency of separating ions with different ion masses. The mass of an atom is approximated to the sum of the masses of protons and neutrons inside, considering the masses of protons and neutrons as equal. However, the masses of the proton (1.6726 × 10−24 g) and neutron (1.6749 × 10−24 g) are not truly equal. There is a minor error in the expression of atomic masses relative to the simplest atom of hydrogen. For example, the mass of helium...
01:15Mass Spectrometry of Amines
In mass spectroscopy, amines undergo fragmentation to give parent ions with odd molecule weights. This observed mass spectrum follows the nitrogen rule; a molecule with an odd number of nitrogen atoms produces a molecular ion with an odd molecular weight. Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit strong molecular ion peaks, but acyclic aliphatic amines show...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
01:33Peptide Identification Using Tandem Mass Spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is an analytical technique that employs two mass analyzers. Essentially it is a series of mass spectrometers that helps isolate a particular biomolecule and then helps study its chemical properties.
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...