key term - D-amino acids

Definition

D-amino acids are a type of amino acid where the amino group is attached to the carbon atom in a configuration that differs from the more common l-amino acids. While l-amino acids are predominant in proteins synthesized by living organisms, d-amino acids play critical roles in various biological functions, including neurotransmission and bacterial cell wall structure. Their unique configuration allows them to participate in specific interactions that are not possible for their l-counterparts.

5 Must Know Facts For Your Next Test

1. D-amino acids can be found in certain peptides and proteins, particularly in bacterial cell walls and some neuroactive substances.
2. Unlike l-amino acids, d-amino acids can be resistant to enzymatic degradation by proteases that specifically target l-forms.
3. The presence of d-amino acids in human tissues has been linked to various physiological processes, including neuroprotection and the modulation of synaptic transmission.
4. Some d-amino acids can act as signaling molecules and are involved in regulating mood and cognitive functions.
5. D-amino acid oxidase is an enzyme that plays a crucial role in the metabolism of d-amino acids, converting them into corresponding keto acids.

Review Questions

• What distinguishes d-amino acids from l-amino acids, and why is this distinction important in biological systems?
  • D-amino acids differ from l-amino acids in their stereochemistry, specifically the orientation of the amino group around the alpha carbon. This distinction is important because it influences how these amino acids interact with enzymes, receptors, and other biomolecules. While l-amino acids are primarily found in proteins, d-amino acids have unique roles in certain biological functions, such as serving as neurotransmitters or contributing to the structure of bacterial cell walls.
• Discuss the potential roles of d-amino acids in human physiology and their significance in neurotransmission.
  • D-amino acids have several roles in human physiology, particularly in neurotransmission where they can function as signaling molecules. For instance, d-serine acts as a co-agonist at NMDA receptors in the brain, influencing synaptic plasticity and cognitive functions. Their involvement in neurotransmission highlights their significance beyond being mere building blocks of proteins; they are essential for modulating various neural processes that affect behavior and cognition.
• Evaluate the implications of d-amino acid metabolism on therapeutic strategies for neurological disorders.
  • The metabolism of d-amino acids has significant implications for therapeutic strategies aimed at neurological disorders. Since certain d-amino acids are involved in synaptic signaling and neuroprotection, understanding their metabolic pathways could lead to novel treatment approaches. For example, targeting d-amino acid oxidase could enhance the availability of d-serine, potentially improving outcomes for conditions like schizophrenia or Alzheimer's disease. This understanding opens avenues for drug development that harness the unique properties of d-amino acids for therapeutic benefits.

Related terms

l-amino acids:

l-amino acids are the naturally occurring amino acids that are incorporated into proteins during translation, characterized by their specific configuration around the alpha carbon.

peptide bonds: Peptide bonds are the covalent bonds formed between amino acids, linking them together to form proteins and polypeptides.

neurotransmitters:

Neurotransmitters are chemical messengers that transmit signals across synapses between neurons, with some d-amino acids acting as neurotransmitters or neuromodulators.