Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration

Biochirality is the subject of distinct branches of science, including biophysics, biochemistry, the stereochemistry of protein folding, neuroscience, brain functional laterality and bioinformatics. At the protein level, biochirality is closely associated with various post-translational modification...

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Main Authors: Victor V. Dyakin, Thomas M. Wisniewski, Abel Lajtha
Format: Article
Language:English
Published: MDPI AG 2020-04-01
Series:Symmetry
Subjects:
Online Access:https://www.mdpi.com/2073-8994/12/4/585
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author Victor V. Dyakin
Thomas M. Wisniewski
Abel Lajtha
author_facet Victor V. Dyakin
Thomas M. Wisniewski
Abel Lajtha
author_sort Victor V. Dyakin
collection DOAJ
description Biochirality is the subject of distinct branches of science, including biophysics, biochemistry, the stereochemistry of protein folding, neuroscience, brain functional laterality and bioinformatics. At the protein level, biochirality is closely associated with various post-translational modifications (PTMs) accompanied by the non-equilibrium phase transitions (PhTs <sup>NE</sup>). PTMs <sup>NE</sup> support the dynamic balance of the prevalent chirality of enzymes and their substrates. The stereoselective nature of most biochemical reactions is evident in the enzymatic (Enz) and spontaneous (Sp) PTMs (PTMs <sup>Enz</sup> and PTMs <sup>Sp</sup>) of proteins. Protein chirality, which embraces biophysics and biochemistry, is a subject of this review. In this broad field, we focus attention to the amyloid-beta (Aβ) peptide, known for its essential cellular functions and associations with neuropathology. The widely discussed amyloid cascade hypothesis (ACH) of Alzheimer’s disease (AD) states that disease pathogenesis is initiated by the oligomerization and subsequent aggregation of the Aβ peptide into plaques. The racemization-induced aggregation of protein and RNA have been extensively studied in the search for the contribution of spontaneous stochastic stereo-specific mechanisms that are common for both kinds of biomolecules. The failure of numerous Aβ drug-targeting therapies requires the reconsolidation of the ACH with the concept of PTMs <sup>Sp</sup>. The progress in methods of chiral discrimination can help overcome previous limitations in the understanding of AD pathogenesis. The primary target of attention becomes the network of stereospecific PTMs that affect the aggregation of many pathogenic agents, including Aβ. Extensive recent experimental results describe the truncated, isomerized and racemized forms of Aβ and the interplay between enzymatic and PTMs <sup>Sp</sup>. Currently, accumulated data suggest that non-enzymatic PTMs <sup>Sp</sup> occur in parallel to an existing metabolic network of enzymatic pathways, meaning that the presence and activity of enzymes does not prevent non-enzymatic reactions from occurring. PTMs <sup>Sp</sup> impact the functions of many proteins and peptides, including Aβ. This is in logical agreement with the silently accepted racemization hypothesis of protein aggregation (RHPA). Therefore, the ACH of AD should be complemented by the concept of PTMs <sup>Sp</sup> and RHPA.
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spelling doaj.art-0d501dc1c8924116bf7be7c3bec852d32023-11-19T20:57:33ZengMDPI AGSymmetry2073-89942020-04-0112458510.3390/sym12040585Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and NeurodegenerationVictor V. Dyakin0Thomas M. Wisniewski1Abel Lajtha2Departmemts: Virtual Reality Perception Lab. (VV. Dyakin) and Center for Neurochemistry (A. Lajtha), The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USADepartments of Neurology, Pathology and Psychiatry, Center for Cognitive Neurology, New York University School of Medicine, New York, NY 10016, USADepartmemts: Virtual Reality Perception Lab. (VV. Dyakin) and Center for Neurochemistry (A. Lajtha), The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USABiochirality is the subject of distinct branches of science, including biophysics, biochemistry, the stereochemistry of protein folding, neuroscience, brain functional laterality and bioinformatics. At the protein level, biochirality is closely associated with various post-translational modifications (PTMs) accompanied by the non-equilibrium phase transitions (PhTs <sup>NE</sup>). PTMs <sup>NE</sup> support the dynamic balance of the prevalent chirality of enzymes and their substrates. The stereoselective nature of most biochemical reactions is evident in the enzymatic (Enz) and spontaneous (Sp) PTMs (PTMs <sup>Enz</sup> and PTMs <sup>Sp</sup>) of proteins. Protein chirality, which embraces biophysics and biochemistry, is a subject of this review. In this broad field, we focus attention to the amyloid-beta (Aβ) peptide, known for its essential cellular functions and associations with neuropathology. The widely discussed amyloid cascade hypothesis (ACH) of Alzheimer’s disease (AD) states that disease pathogenesis is initiated by the oligomerization and subsequent aggregation of the Aβ peptide into plaques. The racemization-induced aggregation of protein and RNA have been extensively studied in the search for the contribution of spontaneous stochastic stereo-specific mechanisms that are common for both kinds of biomolecules. The failure of numerous Aβ drug-targeting therapies requires the reconsolidation of the ACH with the concept of PTMs <sup>Sp</sup>. The progress in methods of chiral discrimination can help overcome previous limitations in the understanding of AD pathogenesis. The primary target of attention becomes the network of stereospecific PTMs that affect the aggregation of many pathogenic agents, including Aβ. Extensive recent experimental results describe the truncated, isomerized and racemized forms of Aβ and the interplay between enzymatic and PTMs <sup>Sp</sup>. Currently, accumulated data suggest that non-enzymatic PTMs <sup>Sp</sup> occur in parallel to an existing metabolic network of enzymatic pathways, meaning that the presence and activity of enzymes does not prevent non-enzymatic reactions from occurring. PTMs <sup>Sp</sup> impact the functions of many proteins and peptides, including Aβ. This is in logical agreement with the silently accepted racemization hypothesis of protein aggregation (RHPA). Therefore, the ACH of AD should be complemented by the concept of PTMs <sup>Sp</sup> and RHPA.https://www.mdpi.com/2073-8994/12/4/585biochiralitypost-translational modificationsprotein foldingprotein aggregationspontaneous chemical reactionsneurodegeneration
spellingShingle Victor V. Dyakin
Thomas M. Wisniewski
Abel Lajtha
Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
Symmetry
biochirality
post-translational modifications
protein folding
protein aggregation
spontaneous chemical reactions
neurodegeneration
title Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
title_full Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
title_fullStr Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
title_full_unstemmed Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
title_short Chiral Interface of Amyloid Beta (Aβ): Relevance to Protein Aging, Aggregation and Neurodegeneration
title_sort chiral interface of amyloid beta aβ relevance to protein aging aggregation and neurodegeneration
topic biochirality
post-translational modifications
protein folding
protein aggregation
spontaneous chemical reactions
neurodegeneration
url https://www.mdpi.com/2073-8994/12/4/585
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