carboxyl

Examples of carboxyl in the following topics:

• Amino Acids

  • An amino acid contains an amino group, a carboxyl group, and an R group, and it combines with other amino acids to form polypeptide chains.
  • The name "amino acid" is derived from the amino group and carboxyl-acid-group in their basic structure.
  • This end is called the N terminal, or the amino terminal, and the other end has a free carboxyl group, also known as the C or carboxyl terminal.
  • The carboxyl group of one amino acid is linked to the amino group of the incoming amino acid.
  • Amino acids have a central asymmetric carbon to which an amino group, a carboxyl group, a hydrogen atom, and a side chain (R group) are attached.

• Peptide Bonding between Amino Acids

  • Amino acids are chemical compounds consisting of a carbon atom bonded to an amine group, a hydrogen atom, a carboxylic group, and a varying side-chain (R group); it is this side chain that distinguishes each amino acid from another.
  • It occurs when the carboxylic group of one molecule reacts with the amino group of the other molecule, linking the two molecules and releasing a water molecule.
  • The blue balls represent the nitrogen that connect from the amine terminus of one amino acid to the carboxylate of another.

• Functional Groups

  • Some of the important functional groups in biological molecules include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups.
  • Among the hydrophilic functional groups is the carboxyl group found in amino acids, some amino acid side chains, and the fatty acid heads that form triglycerides and phospholipids.
  • This carboxyl group ionizes to release hydrogen ions (H+) from the COOH group resulting in the negatively charged COO- group; this contributes to the hydrophilic nature of whatever molecule it is found on.

• Breakdown of Pyruvate

  • A carboxyl group is removed from pyruvate, releasing a molecule of carbon dioxide into the surrounding medium.
  • Each pyruvate molecule loses a carboxylic group in the form of carbon dioxide.

• CAM and C4 Photosynthesis

  • CAM plants store the CO2 mostly in the form of malic acid via carboxylation of phosphoenolpyruvate to oxaloacetate, which is then reduced to malate.
  • Plants that do not use PEP-carboxylase in carbon fixation are called C3 plants because the primary carboxylation reaction, catalyzed by RuBisCO, produces the three-carbon 3-phosphoglyceric acids directly in the Calvin-Benson cycle.

• Regulating Protein Activity and Longevity

  • Methylation on side chain nitrogens is considered largely irreversible while methylation of the carboxyl groups is potentially reversible.
  • Methylation on carboxylate side chains covers up a negative charge and adds hydrophobicity.

• Acetyl CoA to CO2

  • In the presence of oxygen, acetyl CoA delivers its acetyl group to a four-carbon molecule, oxaloacetate, to form citrate, a six-carbon molecule with three carboxyl groups.

• Waxes

  • Animal wax esters are typically derived from a variety of carboxylic acids and fatty alcohols.

• Connecting Proteins to Glucose Metabolism

  • The remaining atoms of the amino acid result in a keto acid: a carbon chain with one ketone and one carboxylic acid group.

• The Energy-Releasing Steps of Glycolysis

  • (This is an example of substrate-level phosphorylation. ) A carbonyl group on the 1,3-bisphosphoglycerate is oxidized to a carboxyl group, and 3-phosphoglycerate is formed.