A protease-resistant D-amino acid αA-crystallin mini-chaperone with enhanced chaperone and antioxidant activities protects against amyloid-β proteotoxicity
- 1Department of Ophthalmology, University of Missouri, Columbia, MO 65212.
- 2Department of Biochemistry, University of Missouri, Columbia, MO 65212.
Abstract
Protein misfolding, aggregation, and oxidative stress contribute to aging and numerous neurodegenerative diseases, including Alzheimer's disease. Although the αA-crystallin-derived mini-chaperone peptide suppresses protein aggregation, its therapeutic potential is limited by susceptibility to proteolytic degradation. Here, we synthesized a protease-resistant analog composed entirely of D-amino acids (D-MC-αA) and compared its biochemical and biological properties with those of the parent peptide (MC-αA). Chaperone activity was assessed using two aggregation-prone model proteins, antioxidant activity by inhibition of Cu 2+ -mediated oxidation of ascorbic acid, and proteolytic stability by enzymatic digestion followed by reverse-phase HPLC. Cytoprotective and membrane-protective activities were evaluated using melittin-induced cytotoxicity in retinal pigment epithelial cells and hemolysis of human red blood cells. Peptide uptake, lifespan, thermotolerance, and protection against amyloid-β toxicity were evaluated in Caenorhabditis elegans ( C . elegans ). D-MC-αA exhibited approximately threefold greater chaperone activity than MC-αA, completely resisted enzymatic degradation, and more effectively inhibited Cu 2+ -mediated ascorbic acid oxidation. Both peptides protected retinal cells against melittin-induced injury and reduced red blood cell hemolysis. The mini-chaperone was efficiently taken up by C . elegans, and both peptides significantly extended lifespan, enhanced thermotolerance, delayed amyloid-β-induced paralysis, and prolonged survival without adversely affecting feeding behavior or reproduction. D-MC-αA provided greater protection than MC-αA against amyloid-β-induced paralysis and mortality. Collectively, these findings demonstrate that all-D-amino acid substitution confers proteolytic resistance, enhances chaperone and antioxidant activities, and preserves cytoprotective function, supporting further development of D-MC-αA for disorders associated with protein misfolding, oxidative stress, and amyloid toxicity.
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BibTeX
@article{srivastava2026proteaseresistant,
title = {{A protease-resistant D-amino acid αA-crystallin mini-chaperone with enhanced chaperone and antioxidant activities protects against amyloid-β proteotoxicity}},
author = {Swati Srivastava and Puttur Santhoshkumar and Tenzin Tender and Krishna Sharma},
journal = {Free radical biology \& medicine},
year = {2026},
month = oct,
doi = {10.1016/j.freeradbiomed.2026.10.032},
url = {https://doi.org/10.1016/j.freeradbiomed.2026.10.032},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - A protease-resistant D-amino acid αA-crystallin mini-chaperone with enhanced chaperone and antioxidant activities protects against amyloid-β proteotoxicity
AU - Swati Srivastava
AU - Puttur Santhoshkumar
AU - Tenzin Tender
AU - Krishna Sharma
PY - 2026
DA - 2026/10/13
JO - Free radical biology & medicine
DO - 10.1016/j.freeradbiomed.2026.10.032
UR - https://doi.org/10.1016/j.freeradbiomed.2026.10.032
AB - Protein misfolding, aggregation, and oxidative stress contribute to aging and numerous neurodegenerative diseases, including Alzheimer's disease. Although the αA-crystallin-derived mini-chaperone peptide suppresses protein aggregation, its therapeutic potential is limited by susceptibility to proteolytic degradation. Here, we synthesized a protease-resistant analog composed entirely of D-amino acids (D-MC-αA) and compared its biochemical and biological properties with those of the parent peptide (MC-αA). Chaperone activity was assessed using two aggregation-prone model proteins, antioxidant activity by inhibition of Cu 2+ -mediated oxidation of ascorbic acid, and proteolytic stability by enzymatic digestion followed by reverse-phase HPLC. Cytoprotective and membrane-protective activities were evaluated using melittin-induced cytotoxicity in retinal pigment epithelial cells and hemolysis of human red blood cells. Peptide uptake, lifespan, thermotolerance, and protection against amyloid-β toxicity were evaluated in Caenorhabditis elegans ( C . elegans ). D-MC-αA exhibited approximately threefold greater chaperone activity than MC-αA, completely resisted enzymatic degradation, and more effectively inhibited Cu 2+ -mediated ascorbic acid oxidation. Both peptides protected retinal cells against melittin-induced injury and reduced red blood cell hemolysis. The mini-chaperone was efficiently taken up by C . elegans, and both peptides significantly extended lifespan, enhanced thermotolerance, delayed amyloid-β-induced paralysis, and prolonged survival without adversely affecting feeding behavior or reproduction. D-MC-αA provided greater protection than MC-αA against amyloid-β-induced paralysis and mortality. Collectively, these findings demonstrate that all-D-amino acid substitution confers proteolytic resistance, enhances chaperone and antioxidant activities, and preserves cytoprotective function, supporting further development of D-MC-αA for disorders associated with protein misfolding, oxidative stress, and amyloid toxicity.
SN - 0891-5849
SN - 1873-4596
ER -