Amino acid sequence

Amino Acid Sequence

The amino acid sequence of a protein is the order in which amino acids are linked together to form a polypeptide chain. This sequence is determined by the genetic code and is crucial for the protein's structure and function.

Structure of Amino Acids

Amino acids are organic compounds that contain both an amino group (-NH₂) and a carboxyl group (-COOH). The general structure of an amino acid can be represented as:

H₂N-CHR-COOH

where "R" represents a side chain specific to each amino acid. There are 20 standard amino acids that are encoded by the universal genetic code.

Importance of Amino Acid Sequence

The sequence of amino acids in a protein determines its three-dimensional structure, which in turn determines its function. Proteins can function as enzymes, structural components, signaling molecules, and more. Even a single change in the amino acid sequence can lead to significant changes in protein function, as seen in diseases such as sickle cell anemia.

Determination of Amino Acid Sequence

The amino acid sequence of a protein can be determined using several methods:

• Edman Degradation: A method of sequencing amino acids in a peptide. In this technique, the amino-terminal residue is labeled and cleaved from the peptide without disrupting the peptide bonds between other amino acid residues.

• Mass Spectrometry: A powerful technique that can determine the mass of peptides and proteins, allowing for the deduction of the amino acid sequence.

• DNA Sequencing: Since the sequence of a protein is encoded by the sequence of nucleotides in DNA, sequencing the corresponding gene can provide the amino acid sequence of the protein.

Applications

Understanding the amino acid sequence of proteins is fundamental in fields such as biotechnology, pharmacology, and genetic engineering. It allows for the design of recombinant proteins, the development of therapeutic antibodies, and the study of protein-protein interactions.

See Also

• Protein structure
• Genetic code
• Peptide synthesis

References

• Berg, J. M., Tymoczko, J. L., & Stryer, L. (2002). Biochemistry. W.H. Freeman.
• Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell. Garland Science.