Related Experiment Video
Updated: May 9, 2026
08:00
DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers
Published on: October 25, 2017
Hyperthin nanochains composed of self-polymerizing protein shackles
Ryo Matsunaga1, Saeko Yanaka, Satoru Nagatoishi
1The Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Nature Communications
|July 26, 2013
Summary
Researchers developed self-polymerizing protein monomers, called protein shackles, that form controllable nanochains. This breakthrough enables stable attachment of functional proteins for advanced nanomaterials.
Area of Science:
- Biomaterials Science
- Nanotechnology
- Protein Engineering
Background:
- Protein fibrils offer sophisticated structures for functional nanomaterials.
- Controlling nanoscale ordering of protein functional units remains a significant challenge.
Purpose of the Study:
- To design self-polymerizing protein monomers (protein shackles) for controlled nanochain formation.
- To investigate the impact of monomer interactions and redox conditions on polymerization.
- To demonstrate the stable attachment and preserved functionality of proteins on nanochains.
Main Methods:
- Engineering recombinant pili subunits from Streptococcus pyogenes into self-polymerizing protein monomers.
- Utilizing spontaneous irreversible covalent bond formation for polymerization.
- Modulating polymerization through redox conditions affecting engineered disulfide bonds.
- Tagging protein shackles with green fluorescent protein to assess protein attachment and functionality.
Main Results:
- Protein shackles polymerized into nanochains via spontaneous covalent bond formation.
- Polymerization was controllable by altering redox conditions via engineered cysteine residues.
- Monomer interactions influenced polymerization reactivity and polymer morphology.
- Green fluorescent protein-tagged shackles polymerized, preserving protein functionality.
- Molecular-recognizable nanochains exhibited enhanced binding in solution.
Conclusions:
- Developed protein shackles enable controlled formation of protein-based nanochains.
- Redox-sensitive disulfide bonds provide a mechanism for controlling polymerization.
- Functional proteins can be stably integrated into nanochains, opening avenues for novel protein nanomaterials.
Related Concept Videos
01:04Anionic Chain-Growth Polymerization: Mechanism
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael acceptor.
01:28ATP and Macromolecule Synthesis
Biological macromolecules are organic compounds, predominantly composed of carbon atoms. The carbon atoms are covalently bonded with hydrogen, oxygen, nitrogen, and other minor elements. There are four major biological macromolecule classes: carbohydrates, lipids, proteins, and nucleic acids.
Most macromolecules are composed of single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
Conversion of...
Most macromolecules are composed of single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
Conversion of...
01:18Assembly of Cytoskeletal Filaments
Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
01:20Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
01:19The Structure of Intermediate Filaments
The intermediate filaments are one of three widely studied cytoskeletal filaments. They are so named as their diameter (10 nm) is in between that of microfilaments (7 nm) and the microtubules (25 nm). These filaments are highly stable and can remain intact when exposed to high salt concentrations and detergents. These filaments are responsible for providing stability and mechanical support to the cells. They also help in cell adhesion and maintaining tissue integrity.
Intermediate filaments...
Intermediate filaments...
02:43Peptide Bonds
A peptide bond covalently attaches amino acids through a dehydration reaction. One amino acid's carboxyl group and another amino acid's amino group combine, releasing a water molecule. The resulting bond is the peptide bond. The products that such linkages form are peptides. As more amino acids join this growing chain, the resulting chain is a polypeptide. Each polypeptide has a free amino group at one end. This end has the N-terminal, or the amino-terminal, and the other end has a free...