Chemical Science Blog

Scientists in Germany have engineered peptide domains with altered substrate specificities, which leads the way for designer templates to make new bioactive products.

The group have studied hormaomycin, a structurally unusual antibiotic peptide, which is biosynthesized by a bacterial nonribosomal peptide synthetase (NRPS). Analysing amino acid residues of hormaomycin had previously revealed that the NRPS adenylation (A) domains naturally recombine during evolution. This inspired the team to create A domains with altered substrates, which in turn has uncovered new information about the NRPS pathway and suggests new strategies in peptide engineering.

Biosynthetic megaenzymes, such as NRPS, are currently of biomedical interest, as they produce a large number of bioactive metabolites via an assembly mechanism, which shows potential for artificial engineering. Nonribosomal peptides have many clinical applications, including antibiotics, antitumour agents and antifungals.

A significant advantage of this evolution-based engineering is that it requires no insight into protein structures, so while not effective for all NRPS systems, the experimental ease of this method makes it a useful addition to engineering techniques.

Read this ‘HOT’ article today:

Evolution-guided engineering of nonribosomal peptide synthetase adenylation domains
Max Crüsemann, Christoph Kohlhaas and Jörn Piel
Chem. Sci., 2012, DOI: 10.1039/C2SC21722H

Scientists in the US and Ireland have developed a new approach to quantitative resistive-pulse sensing, using a nanopipette-based sensor to selectively detect antibodies to peanut allergens (about 1% of Americans suffer from peanut allergies, they say).

Peanut allergens are glycoproteins, and these cause an immune response elevating IgE (Immunoglobulin E) antibody levels in people with a peanut allergy. The increased immunoglobulin levels can be measured by the nanopipette sensor and will help to detect the likelihood of severe allergy episodes.

The nanopipettes work by sensing an analyte as it enters their nanometre-sized pores. The particle must be small enough to fit through the hole, but large enough to cause a measurable change in the recorded ion current. This technique allows label-free detection of antibodies.

Read the ‘HOT’ article:

Resistive-Pulse Measurements with Nanopipettes: Detection of Au Nanoparticles and Nanoparticle-Bound Anti-peanut IgY
Y Wang et al, Chem. Sci., 2012, DOI: 10.1039/c2sc21502k

Unlike conventional electromagnetic interactions, the chemical bond has not been quantified in strength by any known property of the participating species, until now.

Scientists in China say that bond energy (EAB), a quantitative measure of the bond strength, can be decoupled into two contributions of the participating reactants, which is a new principle.

The team verified their theory with more than 300 bonds, including covalent bonds in molecules and adsorption bonds on metal surfaces; this can be applied in a wide range of chemical reactions. Particularly, the characteristic complex quantity, termed ‘chemical amplitude’ can be used to describe accurately the chemical reactivity of both molecules and metal surfaces, which is an advantage when studying heterogeneous catalysis.

The work should allow scientists to make a direct evaluation of the bond energy and also reveal new aspects of the chemical interaction, they say.

Read this ‘HOT’ Chemical Science Edge Article:

Bond-Energy Decoupling: Principle and Application to Heterogeneous
Catalysis Bing Huang , Lin Zhuang , Li Xiao and Juntao Lu
Chem. Sci., 2012, DOI: 10.1039/C2SC21232C