Definition

Noun: * An amino acid that is a fundamental component of many proteins, most notably collagen. It is unique among the standard amino acids because its side chain forms a cyclic structure, linking back to the amino group. This structure influences the shape and stability of proteins.

Usage

• Proline is a non-essential amino acid, meaning the human body can synthesize it.
• The presence of proline in a protein chain often causes a bend or kink in its structure.
• High concentrations of proline are found in connective tissues like collagen and elastin.

Examples

• The protein collagen is particularly rich in the amino acid proline.
• Researchers studied the role of proline in plant stress responses.
• A mutation that alters a proline residue can disrupt the proper folding of a protein.

Advanced Usage

• Proline-rich regions: Specific sequences in a protein that contain a high frequency of proline residues, often involved in protein-protein interactions.
  • The transcription factor contains a proline-rich activation domain.
• Proline isomerization: The process where proline switches between two distinct ring conformations (cis and trans), which can be a rate-limiting step in protein folding.
  • The enzyme catalyzes proline isomerization to assist in protein folding.

Variants and Related Words

• Hydroxyproline (noun): A modified form of proline that contains an additional hydroxyl (-OH) group. It is a critical component of collagen and is formed by an enzymatic reaction after proline is incorporated into the protein chain.
  • Hydroxyproline provides additional stability to the collagen triple helix.

Synonyms

• Amino acid (general category)
• Imino acid (specific chemical classification due to its cyclic structure)

Related Terms and Concepts

• Collagen: The primary structural protein in connective tissue, characterized by its high proline and glycine content.
• Protein synthesis: The cellular process of building proteins, during which proline is incorporated by its specific transfer RNA (tRNA).
• Secondary structure: The local folded structures in a protein, such as alpha helices and beta sheets, which are influenced by proline's ability to disrupt regular patterns.

Noun

1. an amino acid that is found in many proteins (especially collagen)