Is there D-amino acid on protein structure? 

Yes, D-amino acids can be found in protein structures, although traditionally proteins were believed to consist solely of L-amino acids. Recent research has revealed the presence of D-amino acid residues in proteins, which can impact protein structure and function. These D-amino acids have been identified in various peptides synthesized by animal cells, including peptides with neuroexcitatory, neuroprotective, and antimicrobial properties. The discovery of D-amino acid-containing peptides (DAACPs) in diseases like cataracts and Alzheimer's highlights their potential role as biomarkers and drug targets. Advanced analytical techniques, such as 2D-HPLC-MS/MS, have been developed to detect trace amounts of D-amino acid residues in proteins, aiding in understanding their significance in protein structures and functions. The incorporation of D-amino acids in proteins challenges the traditional view of protein composition and opens new avenues for research into their roles in health and disease.

Biogenesis of D-amino acid containing peptides/proteins: where, when and how?

Yes, D-amino acids can be found in protein structures, leading to the formation of D-amino acid containing peptides/proteins through enzymatic posttranslational modifications like peptidyl aminoacyl l-d isomerisation.

Establishment of a Two-Dimensional HPLC-MS/MS Method Combined with DCl/D 2 O Hydrolysis for the Determination of Trace Amounts of D-Amino Acid Residues in Proteins

Yes, the study established a method to determine trace amounts of D-amino acid residues in proteins, highlighting the presence of D-Ser in ovalbumin protein structure.

D-amino acids in foods.

D-amino acids are not typically found in protein structures; however, they play specific roles in various organisms, such as in bacterial cell walls and mammalian neurotransmission.

D-Amino Acids in Peptides from Animals, Including Human: Occurrence, Structure, Bioactivity and Pharmacology.

Yes, D-amino acids are found in peptides from animals, including humans, despite proteins being primarily composed of L-amino acids. This occurrence is discussed in the paper.

D-Amino Acids and D-Amino Acid-Containing Peptides: Potential Disease Biomarkers and Therapeutic Targets?

Yes, D-amino acids can be present in protein structures, affecting their function. The conversion between L and D forms can alter protein activity, potentially influencing disease development.