depsipeptide

A depsipeptide is a peptide in which one or more of the amide (-CONHR-) bonds are replaced by ester (COOR) bonds.Depsipeptides have often been used in research to probe the importance of hydrogen bond networks in protein folding kinetics and thermodynamics. They are also found in nature as natural products. An infamous example is the L-Lys-D-Ala-D-Lac motif found in vancomycin resistant bacteria's cell wall building blocks. The amide to ester mutation disrupts its hydrogen bonding network with vancomycin, which is key to the antibiotic's activity.
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A substance that is made naturally by some bacteria, fungi, and other organisms, and can also be made in the laboratory. Depsipeptides are being studied in the treatment of cancer.