Humanin (HN), a peptide of 24 amino acid residues, suppresses the neuronal cell death that is induced by the gene products of Alzheimer's disease. HN contains two Ser residues at positions 7 and 14. Because the proportion of D-Ser isomerized from L-Ser in proteins appears to increase as cellular organs age, we explored the structural effects of the isomerization of each Ser residue in HN. By using a thioflavin-T assay to detect fibril formation, we found that an HN derivative that contained two isomerized D-Ser residues had a greater tendency to form fibrils than did wild-type HN or HNs containing single D-Ser residues. A previous report showed that HN containing two D-Ser residues exerts neuroprotective activity. Our data, therefore, suggest that the fibril formation by HN that contains two D-Ser residues may promote HN neuroprotective activity.
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http://dx.doi.org/10.1007/s00726-011-0971-6 | DOI Listing |
Anal Sci
May 2024
School of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, 513-8670, Japan.
Stereoinversion of Ser residues within proteins, which has been identified in long-lived proteins, influences protein function. To quantify the stereoinversion of Ser residues, we investigated the potential adaptation of our direct peptide analytical method originally established for analyzing the isomerization of asparaginyl/aspartyl residues. Peptide pairs containing L-Ser or D-Ser residues with lengths of four or five residues were synthesized.
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January 2024
Department of Chemistry, University of California-Riverside Riverside CA 92521 USA
An indirect competitive binding mechanism can be exploited to allow a combination of cationic fluorophores and water-soluble synthetic receptors to selectively recognize and discriminate peptide strands containing a single isomeric residue in the backbone. Peptide isomerization occurs in long-lived proteins and has been linked with diseases such as Alzheimer's, cataracts and cancer, so isomers are valuable yet underexplored targets for selective recognition. Planar cationic fluorophores can selectively bind hydrophobic, Trp-containing peptide strands in solution, and when paired with receptors that provide a competitive host for the fluorophore, can form a differential sensing array that enables selective discrimination of peptide isomers.
View Article and Find Full Text PDFAnal Bioanal Chem
November 2023
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX, 76019, USA.
While the existence of D-amino acids in peptides and proteins has recently been accepted in higher forms of life, their roles and importance are yet to be understood. The lack of analytical methods present for such epimeric and/or isomeric analyses often limits developments in the field. Studies have shown the elevated presence of epimeric and isomeric modifications to amyloid-beta (Aβ) peptides extracted from Alzheimer's disease patients.
View Article and Find Full Text PDFSci Rep
July 2023
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX, 76019, USA.
Extracellular deposition of amyloid beta (Aβ) peptide is a contributing factor of Alzheimer's disease (AD). Considerable effort has been expended to create effective antibodies, or immunotherapies, targeting Aβ peptides. A few immunotherapies are thought to provide some benefit.
View Article and Find Full Text PDFComput Biol Med
June 2023
Structural Bioinformatics Unit, Department of Biochemistry, Shivaji University, Vidyanagar, Kolhapur, 416004, Maharashtra, India; Department of Microbiology, Shivaji University, Vidyanagar, Kolhapur, 416004, Maharashtra, India; Department of Chemistry, Shivaji University, Vidyanagar, Kolhapur, 416004, Maharashtra, India. Electronic address:
Vancomycin resistance in enterococci mainly arises due to alteration in terminal peptidoglycan dipeptide. A comprehensive structural analysis for substrate specificity of dipeptide modifying d-Alanine: d-Serine ligase (Ddls) is essential to screen its inhibitors for combating vancomycin resistance. In this study modeled 3D structure of EgDdls from E.
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