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Related Concept Videos

Amino Acid Catabolism01:18

Amino Acid Catabolism

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Microorganisms rely on proteins as an essential carbon and energy source, particularly in environments with limited polysaccharides or lipids. However, proteins are too large to cross the plasma membrane unaided, necessitating enzymatic degradation. Microbes secrete extracellular proteases and peptidases that hydrolyze proteins into peptides, which can then be transported across the membrane. Once inside the cell, intracellular proteases degrade these peptides into free amino acids, which...
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Acetoacetic ester synthesis is a method to obtain ketones from alkyl halides and β-keto esters. The reaction occurs in the presence of an alkoxide base that abstracts the acidic proton of the β-keto esters. The step results in an enolate ion which is doubly stabilized. The enolate then reacts with an alkyl halide via the SN2 process to produce an alkylated ester intermediate with a new C–C bond. The hydrolysis of the intermediate, followed by acidification, results in an...
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Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
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α-Alkylation of Ketones via Enolate Ions01:10

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Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the...
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Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
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Amides are synthesized by treating carboxylic acids with amines in the presence of dehydrating agents like dicyclohexylcarbodiimide (DCC).
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C-Terminal lactamization of peptides.

Niklas H Fischer1, Daniel S Nielsen1, Daniel Palmer1

  • 1Center for Evolutionary Chemical Biology, Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark. fdi@chem.ku.dk meldal@chem.ku.dk.

Chemical Communications (Cambridge, England)
|December 28, 2020
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Summary

Solid-phase synthesis of peptides (SPPS) was achieved using C-terminal lactam formation for release. Synthesized lactamized peptides showed enhanced bio-stability and maintained biological activity compared to traditional peptide amides.

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Area of Science:

  • Organic Chemistry
  • Medicinal Chemistry
  • Biochemistry

Background:

  • Solid-phase peptide synthesis (SPPS) is a cornerstone of peptide chemistry.
  • Developing novel peptide modifications can enhance stability and therapeutic potential.
  • C-terminal lactamization offers a unique strategy for peptide cyclization and stabilization.

Purpose of the Study:

  • To present a novel solid-phase synthesis method for peptides utilizing C-terminal lactam formation for release.
  • To synthesize and characterize natural products ciliatamide A and C using this new methodology.
  • To evaluate the impact of C-terminal lactamization on peptide bio-stability and biological activity.

Main Methods:

  • Solid-phase peptide synthesis (SPPS) employing lactam ring formation (γ-, δ-, or ε-lactams) for peptide cleavage.
  • Synthesis of natural products ciliatamide A and C.
  • Comparative analysis of bio-stability and biological activity between lactamized peptides and parent peptide amides.

Main Results:

  • Successful solid-phase synthesis of peptides with C-terminal lactam release.
  • High yields (up to 90%) achieved in the synthesis of ciliatamide A and C.
  • Lactamized peptides demonstrated significantly increased bio-stability.
  • Comparable biological activity was observed between lactamized peptides and their non-lactamized counterparts.

Conclusions:

  • C-terminal lactamization is an effective strategy for stabilizing peptides synthesized via SPPS.
  • This method provides a viable route for producing stable peptide analogs with preserved bioactivity.
  • The synthesized natural products, ciliatamide A and C, validate the utility of this approach.