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Esters & Amides
Esters & Amides
These functional groups comprise many of the bonds that make up complex molecules within us, including fats, nucleic acids, and proteins.
  • Esters
  • Thioesters
  • Phosphoesters
  • Amides

Esters & Amides

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common functional groups in biochemistry
These functional groups define common molecules, compounds, and reactions in biochemistry, including biochemical polymers such as proteins, DNA and carbohydrates.
FOUR GROUPS
  • Carbon-oxygen groups
  • Carbon-nitrogen groups
  • Carbon-sulfur groups
  • Esters & Amides
Esters (& Amides)
Comprise many of the types of bonds found in the body.
Ester
  • We draw C double-bond O, with an R group and another oxygen attached to the carbon and another R group attached to that oxygen atom.
Esters are formed when carboxylic acids and alcohols react, and include glycerides and fats.
Esters are also major components of many scents and odors (as are aldehydes).
Variations of esters: thioesters, phosphoesters, and amides.
Thioester
  • The sulfur variant of an ester
It is an ester with a sulfur atom in place of the single-bonded oxygen.
Thioesters are intermediates in a number of biosynthetic reactions, including the formation and degradation of fatty acids and steroids. The most commonly known thioester is acetyl CoA, the ester form of coenzyme A, which plays a major role in the Krebs cycle (as does coenzyme A, described previously).
Phosphoester
  • The phosphorus variant of ester
It includes a phosphorous atom instead of carbon. We draw a phosphorus (P) with four attachments: a double-bonded oxygen, two alcohol groups, and an oxygen. We add an R group as the second bond of the oxygen atom.
Phosphoesters are most commonly found in the body as phosphodiesters meaning that instead of one of the alcohol groups, there is another O-R bond. Phosphodiesters are the bonds that link bases together to form nucleic acids (DNA and RNA).
Amides
  • The nitrogen variant of an ester.
Draw a C double-bond O. Add an N bound to the carbon and an R bound to the N. As the third bond on nitrogen, add a hydrogen, and as the fourth bond on carbon add another R group.
Amide bonds are also called peptide bonds, because they are the bonds that join amino acids together in primary protein structure, the most basic structure of proteins. They are formed by the reaction of amines and carboxylic acids.

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