What is Chemoselective ligation?
Chemoselective ligation and modification strategies are important methods for linking synthetic or recombinant unprotected peptides to generate large polypeptides (see scheme). Recent developments in this research area have led to numerous applications in the semisynthesis and total synthesis of proteins.
What is peptide ligation?
51, p. 311). Orthogonal peptide ligation is an amino terminal specific method to couple chemically unprotected peptides or proteins derived from synthetic or biosynthetic sources.
How does expressed protein ligation work?
The expressed protein ligation strategy. Intein cleavage generates the formation of a recombinant protein thioester fragment. This thioester fragment is then mixed with a synthetic N-terminal Cys containing peptide affording a semisynthetic protein via the native chemical ligation reaction.
What is ligation chemically What kind of reaction is this?
Chemical ligation is a set of techniques used for creating long peptide or protein chains. It is the second step of a convergent approach. First, smaller peptides containing 30-50 amino acids are prepared by conventional chemical peptide synthesis. Then, they are completely deprotected.
What are ligases give examples?
Ligase is an enzyme that catalyzes the binding of two molecules. An example is a DNA ligase that links two fragments of DNA by forming a phosphodiester bond.
How long is a peptide?
Peptides are smaller than proteins. Traditionally, peptides are defined as molecules that consist of between 2 and 50 amino acids, whereas proteins are made up of 50 or more amino acids.
What is protein Semisynthesis?
Protein semisynthesis—defined herein as the assembly of a protein from a combination of synthetic and recombinant fragments—is a burgeoning field of chemical biology that has impacted many areas in the life sciences.
Who invented Merrifield resin?
Robert Bruce Merrifield
Merrifield resin is named after its inventor, Robert Bruce Merrifield (1984 winner of the Nobel Prize in Chemistry), and used in solid-phase synthesis.
Why do we use native chemical ligation?
Native chemical ligation is effective at conjugating two peptides together in aqueous solution to form a longer peptide. The reaction proceeds at physiological pH under mild conditions without any additional additives, except for the presence of the thioester-containing peptide and the cysteine-containing peptide.
How is Selenocysteine made?
In contrast to the 20 standard amino acids, selenocysteine is synthesized from a serine precursor through a series of reactions taking place on its unique tRNA.
What is the chemical ligation of peptides?
Chemical ligation is the technique of coupling these peptides by chemoselective reaction to give a unique reaction product, usually in aqueous solution. With several coupling steps, proteins of up to 200-300 amino acids can be produced. There are various techniques described in literature.
Why is native chemical ligation regioselective?
Native chemical ligation is exquisitely regioselective because that thiol (ate)–thioester exchange step is freely reversible in the presence of an exogenous thiol added as catalyst.
What are the ligation additives for plasmid ligation?
If it is necessary to use additives in plasmid ligation, the use of PEG is preferable as it can promote intramolecular as well as intermolecular ligation. The higher the ligase concentration, the faster the rate of ligation.
What is the most powerful ligation method for protein synthesis?
Especially, NCL is the most powerful ligation method for synthesizing native backbone proteins or modified proteins of moderate size ( i.e., small proteins < 200 AA).