Abstract
Peptides and their conjugates (to lipids, bulky N-terminals, or other groups) can self-assemble into nanostructures such as fibrils, nanotubes, coiled coil bundles, and micelles, and these can be used as platforms to present functional residues in order to catalyze a diversity of reactions. Peptide structures can be used to template catalytic sites inspired by those present in natural enzymes as well as simpler constructs using individual catalytic amino acids, especially proline and histidine. The literature on the use of peptide (and peptide conjugate) α-helical and β-sheet structures as well as turn or disordered peptides in the biocatalysis of a range of organic reactions including hydrolysis and a variety of coupling reactions (e.g., aldol reactions) is reviewed. The simpler design rules for peptide structures compared to those of folded proteins permit ready ab initio design (minimalist approach) of effective catalytic structures that mimic the binding pockets of natural enzymes or which simply present catalytic motifs at high density on nanostructure scaffolds. Research on these topics is summarized, along with a discussion of metal nanoparticle catalysts templated by peptide nanostructures, especially fibrils. Research showing the high activities of different classes of peptides in catalyzing many reactions is highlighted. Advances in peptide design and synthesis methods mean they hold great potential for future developments of effective bioinspired and biocompatible catalysts.
Highlights
Biocatalysis refers to the enhancement of the rate of reactions stimulated by biological molecules or their components such as proteins and peptides
This group showed that C12VVAGHH-NH2 forms fibrils that can catalyze Cu2+ click reactions to fluorescently label live cells with streptavidinFITC [FITC: fluorescein isothiocyanate] via reaction with cells bearing biotin-azide reacted with alkyne sialic acid chains in the membrane, as shown schematically in Figure 9.168 The morphology of lipopeptides C16-XYL3K3 can be switched from micelles at pH 7 to fibrils at pH 10.5.169 These molecules are able to bind heme, and the heme active site is available in both micelles and fibers to bind carbon monoxide; unexpectedly peroxidase activity was observed in heme-containing micelles yet was significantly reduced in heme-containing fibers, which was ascribed to a reduced ability to generate reactive oxygen species
This Review shows the considerable potential that selfassembled peptides have in the catalysis of many types of reactions in organic chemistry
Summary
Biocatalysis refers to the enhancement of the rate of reactions stimulated by biological molecules or their components such as proteins and peptides. The majority of enzymes are biocatalytic proteins, which have evolved to have a diversity of functions in nature.[1−3] Enzymes have been harnessed for use in many industries including the production of food and beverages, biofuels, paper, detergents, and others As well as their functionality in vivo, some proteins and peptides have been shown to have strong activity in organocatalysis, i.e. as catalysts of organic reactions in both aqueous and nonaqueous solvents. Several classes of peptides including surfactant-like peptides, amyloid peptides, and lipopeptides (a type of peptide amphiphile) can aggregate in aqueous solution into a range of nanostructures depending on intermolecular forces, especially hydrophobic interactions which are balanced by hydrogenbonding, electrostatic, and π-stacking interactions leading to different self-assembled morphologies This behavior has been reviewed in detail elsewhere.[4−11] The present Review is focused on the use of self-assembled peptide structures in biocatalysis.
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