Proteins are made up of 20 standard building blocks known as amino acids. These amino acids are linked together in long chains via peptide bonds, which are a type of covalent bond. The peptide bond forms between the amino group (-NH₂) of one amino acid and the carboxyl group (-COOH) of another, releasing a molecule of water in the process (a dehydration reaction).
In addition to peptide bonds, proteins can also have various types of interactions and bonds that stabilize their three-dimensional structure, including:
- Hydrogen bonds - These can occur between polar side chains or between backbone atoms in the protein structure.
- Ionic bonds (salt bridges) - These occur between positively and negatively charged side chains.
- Hydrophobic interactions - Non-polar side chains tend to aggregate away from water, stabilizing the protein's structure.
- Disulfide bonds (bridges) - These covalent bonds form between the sulfur atoms of cysteine residues, contributing to the protein’s stability.
Thus, while proteins are primarily constructed from 20 amino acids connected by peptide bonds, various other interactions also play significant roles in maintaining their functional conformation.
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