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α-Amanitin Bacitracin Ciclosporin. Cyclic peptides are polypeptide chains which contain a circular sequence of bonds. [1] This can be through a connection between the amino and carboxyl ends of the peptide, for example in cyclosporin; a connection between the amino end and a side chain, for example in bacitracin; the carboxyl end and a side chain, for example in colistin; or two side chains ...
[3] Circular peptides tend to be resistant to protease activity, and may be suitable for use as orally administered drugs. Once a cyclic peptide is identified with a biological activity of interest, it may also be possible to identify the target of the peptide (a gene that encodes a protein with which it interacts) by functional complementation ...
One of the interesting features of cyclic peptides is that knowledge of the peptide sequence does not reveal the ancestral head and tail; knowledge of the gene sequence is required for this. [5] In the case of kalata B1 the indicated glycine (G) and asparagine (N) amino acids are the terminal residues that are linked in a peptide bond to ...
Cyclic glycine-proline (cGP) is a small neuroactive peptide that belongs to a group of bioactive 2,5-diketopiperazines (2,5-DKPs) and is also known as cyclo-glycine-proline. cGP is a neutral, stable naturally occurring compound and is endogenous to the human body; found in human plasma, breast milk and cerebrospinal fluid.
Each nonribosomal peptide synthetase can synthesize only one type of peptide. Nonribosomal peptides often have cyclic and/or branched structures, can contain non-proteinogenic amino acids including D-amino acids, carry modifications like N-methyl and N-formyl groups, or are glycosylated, acylated, halogenated, or hydroxylated.
Glycopeptide antibiotics are a class of drugs of microbial origin that are composed of glycosylated cyclic or polycyclic nonribosomal peptides.Significant glycopeptide antibiotics include the anti-infective antibiotics vancomycin, teicoplanin, telavancin, ramoplanin, avoparcin and decaplanin, corbomycin, complestatin and the antitumor antibiotic bleomycin.
One of the main reasons for such rapid clearance is molecular weight. Molecules that have a low molecular weight (40-50 kDa) are rapidly cleared by renal filtration via the glomerular filtration barrier (GBM) into the urine. As a result of this, increasing the size of a peptide drug is a good starting point to improve half-life. [12]
DKP's are the smallest known class of cyclic peptide. [1] Despite their name, they are not ketones, but amides. Three regioisomers are possible, differing in the locations of the carbonyl groups. Retosiban [2] is a diketopiperazine being investigated as an oral drug. One isomer is an oxamide obtained from ethylenediamine.