Related Experiment Video

Updated: Aug 29, 2026

Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities
11:44

Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities

Published on: October 2, 2018

Three-dimensional structure of the mini-M conotoxin mr3a

Owen M McDougal1, C Dale Poulter

  • 1Department of Chemistry, Southern Oregon University, Ashland, Oregon 97520, USA.

Biochemistry
|January 14, 2004
PubMed

Insights

Conotoxin mr3a, a novel peptide from Conus marmoreus venom, induces seizures and possesses a unique "triple-turn" backbone structure. Its distinct disulfide bond connectivity differentiates it from other conopeptides.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Neuroscience

Background:

  • Conotoxins are peptides from Conus snail venom with diverse biological activities.
  • The M superfamily of conopeptides includes mu- and psi-conotoxins with known structures and disulfide bond connectivity.

Purpose of the Study:

  • To determine the tertiary structure of conotoxin mr3a.
  • To characterize conotoxin mr3a as a novel mini-M conopeptide.

Main Methods:

  • 2D 1H NMR spectroscopy to determine the tertiary structure.
  • Standard distance-geometry algorithm combined with NMR constraints (NOE, hydrogen bonds, dihedral angles, disulfide bonds).

Main Results:

  • The tertiary structure of conotoxin mr3a was elucidated, revealing a unique "triple-turn" backbone.
  • Conotoxin mr3a exhibits a novel disulfide bond connectivity, distinct from mu- and psi-conotoxins.
  • mr3a was identified as the first member of the mini-M branch of conopeptides.

Conclusions:

  • Conotoxin mr3a represents a new structural subclass within the M conopeptide superfamily.
  • The unique structure of mr3a may contribute to its observed biological activity, including seizure induction.

More Related Videos

Rapid Isolation of the Mitoribosome from HEK Cells09:33

Rapid Isolation of the Mitoribosome from HEK Cells

Published on: October 4, 2018

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy08:27

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Published on: January 7, 2019

Related Concept Videos

Nucleic Acid Structure01:25

Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose's second carbon and a hydrogen on the deoxyribose's second carbon. The phosphate residue attaches to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms  a 5′ to 3′ phosphodiester linkage.
DNA Structure
DNA has a double-helix structure. The...
RNA Structure01:19

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
Different Types of RNA Have the Same Basic Structure
There are three main types of ribonucleic acid (RNA) involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). All three...
RNA Structure01:23

RNA Structure

Overview
The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
Different Types of RNA Have the Same Basic Structure
There are three main types of ribonucleic acid (RNA): messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). All three RNA types consist of a...
RNA Structure01:23

RNA Structure

Overview
The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
Different Types of RNA Have the Same Basic Structure
There are three main types of ribonucleic acid (RNA): messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). All three RNA types consist of a...
Protein Organization01:28

Protein Organization

Proteins are one of the fundamental building blocks of life that carry out many diverse functions in the cell. Proteins are assembled from amino acids. The sequence of amino acids is known as the primary structure of a protein. Local interactions of individual amino acids cause the linear chain to fold into the secondary structures. Interactions of distant amino acids lead to further folding of the protein—the tertiary structure. The assembly of multiple folded chains (subunits) is known as...
Protein Organization01:24

Protein Organization

Proteins are polymers of amino acid residues. They are versatile and responsible for different cellular functions, including DNA replication, molecular transport, catalysis, and structural support. Proteins have a hierarchical structure comprising at least three levels of organization: primary, secondary, and tertiary structure. Some large proteins have a quaternary structure where individual protein subunits are linked together.
The primary structure of a protein is its amino acid sequence.