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Ludwig, Brice A.

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Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation./
Author:	Ludwig, Brice A.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
Description:	419 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-07, Section: B.
Contained By:	Dissertations Abstracts International85-07B.
Subject:	Biochemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30695743
ISBN:	9798381422573

Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation.
Ludwig, Brice A.

Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 419 p.

Source: Dissertations Abstracts International, Volume: 85-07, Section: B.

Thesis (Ph.D.)--University of Delaware, 2023.

This item must not be sold to any third party vendors.

The chemical synthesis of proteins allows for the generation of uniquely modified proteins of interest that may contain novel functionalities or defined patterns of post-translational modifications. Peptide synthesis, combined with native chemical ligation, has been widely used in recent decades in order to overcome the limitations of standard protein expression. The native chemical ligation reaction proceeds across two major processes. In the first process, a C-terminal thioester on one peptide or protein undergoes transthioesterification with an N-terminal thiol or selenol group of a second peptide or protein, resulting in the formation of an S-acyl intermediate. In the second process, the free amine of the second peptide or protein attacks the carbonyl of the S-acyl thioester, inducing an S{acute}{86}{92}N acyl transfer that results in the formation of a native amide bond between the two ligation partners.Originally developed using N-terminal cysteine, native chemical ligation has since been expanded to include synthetic chalcogenated surrogates of all canonical amino acids, alleviating the need for a cysteine at the ligation junction. However, many of these surrogates require long solution-phase syntheses with low yields, or are prohibitively expensive, limiting their use in wider applications. Moreover, some of these surrogates contribute to lengthy reaction times in native chemical ligation due to the unfavorable energies of intermediates in the transthioesterification or S{acute}{86}{92}N acyl transfer mechanisms. These obstacles are particularly prevalent in previously described native chemical ligation reactions using proline or phenylalanine surrogates. Seeking to overcome both of these challenges, we have developed novel solid-phase{A0}{A0}syntheses for 4R-mercaptoproline, 4R-selenoproline, and 2-thiophenylalanine that are practical and accessible. Moreover, in native chemical ligation reactions using proline, we have established optimized ligation conditions to promote fast S{acute}{86}{92}N acyl transfer.The structure and function of a protein is dictated by its amino acid composition. The 20 canonical amino acids confer specific functionality in a protein based on the properties of their side chains. These functionalities contribute to crucial functions such as molecular recognition and protein folding. Proline, in particular, is unique among amino acids because of its cyclic structure. Proline also has a greatly increased propensity over the other amino acids to form cis amide bond conformations. As a result of these unique properties, proline often contributes to protein secondary structure, in cases such as polyproline helices, turns, and loop regions. Proline is also highly conserved in intrinsically disordered proteins and disordered regions of proteins. One such intrinsically disordered protein is the microtubule-associated protein tau, which is implicated in Alzheimer's disease and other neurological diseases. The proline-rich domain of tau contains many phosphorylation sites that are implicated in disease. However, the specific structural and functional mechanisms by which phosphorylation in this region contributes to disease progression are not well understood. In exploring the effects of phosphorylation on peptides derived from the proline-rich domain of tau, we found that the peptide tau211-238 experiences concentration-independent autoproteolysis. This phenomenon is likely to result from conformational changes in the cis-trans isomerization of prolines. We also explored the use of a novel 19F NMR probe of proline conformation to better understand how the structural effects of phosphorylation and a key tau mutation may contribute to disease progression.

ISBN: 9798381422573Subjects--Topical Terms:

518028
Biochemistry.
Subjects--Index Terms:

Peptide synthesis

Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation.
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100 1 $a Ludwig, Brice A. $3 3766816
245 1 0 $a Novel Approaches to Amino Acids for the Chemical Synthesis of Proteins and Insights into the Mechanisms of Tau Aggregation.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
300 $a 419 p.
500 $a Source: Dissertations Abstracts International, Volume: 85-07, Section: B.
500 $a Advisor: Zondlo, Neal J.
502 $a Thesis (Ph.D.)--University of Delaware, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a The chemical synthesis of proteins allows for the generation of uniquely modified proteins of interest that may contain novel functionalities or defined patterns of post-translational modifications. Peptide synthesis, combined with native chemical ligation, has been widely used in recent decades in order to overcome the limitations of standard protein expression. The native chemical ligation reaction proceeds across two major processes. In the first process, a C-terminal thioester on one peptide or protein undergoes transthioesterification with an N-terminal thiol or selenol group of a second peptide or protein, resulting in the formation of an S-acyl intermediate. In the second process, the free amine of the second peptide or protein attacks the carbonyl of the S-acyl thioester, inducing an S{acute}{86}{92}N acyl transfer that results in the formation of a native amide bond between the two ligation partners.Originally developed using N-terminal cysteine, native chemical ligation has since been expanded to include synthetic chalcogenated surrogates of all canonical amino acids, alleviating the need for a cysteine at the ligation junction. However, many of these surrogates require long solution-phase syntheses with low yields, or are prohibitively expensive, limiting their use in wider applications. Moreover, some of these surrogates contribute to lengthy reaction times in native chemical ligation due to the unfavorable energies of intermediates in the transthioesterification or S{acute}{86}{92}N acyl transfer mechanisms. These obstacles are particularly prevalent in previously described native chemical ligation reactions using proline or phenylalanine surrogates. Seeking to overcome both of these challenges, we have developed novel solid-phase{A0}{A0}syntheses for 4R-mercaptoproline, 4R-selenoproline, and 2-thiophenylalanine that are practical and accessible. Moreover, in native chemical ligation reactions using proline, we have established optimized ligation conditions to promote fast S{acute}{86}{92}N acyl transfer.The structure and function of a protein is dictated by its amino acid composition. The 20 canonical amino acids confer specific functionality in a protein based on the properties of their side chains. These functionalities contribute to crucial functions such as molecular recognition and protein folding. Proline, in particular, is unique among amino acids because of its cyclic structure. Proline also has a greatly increased propensity over the other amino acids to form cis amide bond conformations. As a result of these unique properties, proline often contributes to protein secondary structure, in cases such as polyproline helices, turns, and loop regions. Proline is also highly conserved in intrinsically disordered proteins and disordered regions of proteins. One such intrinsically disordered protein is the microtubule-associated protein tau, which is implicated in Alzheimer's disease and other neurological diseases. The proline-rich domain of tau contains many phosphorylation sites that are implicated in disease. However, the specific structural and functional mechanisms by which phosphorylation in this region contributes to disease progression are not well understood. In exploring the effects of phosphorylation on peptides derived from the proline-rich domain of tau, we found that the peptide tau211-238 experiences concentration-independent autoproteolysis. This phenomenon is likely to result from conformational changes in the cis-trans isomerization of prolines. We also explored the use of a novel 19F NMR probe of proline conformation to better understand how the structural effects of phosphorylation and a key tau mutation may contribute to disease progression.
590 $a School code: 0060.
650 4 $a Biochemistry. $3 518028
650 4 $a Organic chemistry. $3 523952
650 4 $a Polymer chemistry. $3 3173488
653 $a Peptide synthesis
653 $a Chemical ligation
653 $a Novel functionalities
653 $a Proline
653 $a Autoproteolysis
690 $a 0487
690 $a 0490
690 $a 0495
710 2 $a University of Delaware. $b Chemistry and Biochemistry. $3 3174095
773 0 $t Dissertations Abstracts International $g 85-07B.
790 $a 0060
791 $a Ph.D.
792 $a 2023
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30695743