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Date Permissions Signed
8-13-2018
Date of Award
Summer 2018
Document Type
Masters Thesis
Degree Name
Master of Science (MS)
Department
Chemistry
First Advisor
Anthony-Cahill,Spencer J.
Second Advisor
Spiegel, P. Clint
Third Advisor
Antos, John M.
Abstract
Polymerized hemoglobin (poly-Hb) molecules have been shown to have reduced toxicity compared to cell-free hemoglobins when transfused intravenously. Poly-Hbs are typically generated with non-specific crosslinking agents that yield a product that is polydisperse in molecular weight. We propose a chemoenzymatic approach to generate poly-Hb of defined molecular weight. The proposed method employs the site-specific ligation reaction of the sortase A enzyme from S. aureus. A Hb mutant previously developed in our lab has been “sortagged” – modified by adding either the sortase recognition sequence (LPXTG) to the C-terminus of the α-subunit or a tetraglycine motif (GGGG) to the N-terminus. We show here that Hb subunits can be ligated directly by sortase A, using a mixture of substrate tagged (LPXTG) and nucleophile tagged (poly-G) Hbs. Additionally, using a novel approach for crosslinking Hb subunits using sortase A, we have generated a di-α construct that is functionalized with a strained cycloalkyne through an unnatural C-to-C fusion of sortagged α-subunits using a bifunctional sortase nucleophile peptide. We show that cycloalkyne-modified Hb molecules can be covalently linked to an azide functionalized fluorescein, using the well-established method of Huisgen cycloaddition. The work presented here establishes the feasibility of generating a monodisperse poly-Hb using azide decorated scaffolds.
Type
Text
Keywords
HBOCs, blood substitute, hemoglobin-based oxygen carriers, polymerized hemoglobins, poly-Hbs, RBC substitute, red blood cell substitute
DOI
https://doi.org/10.25710/gdsw-8274
Publisher
Western Washington University
OCLC Number
1049152445
Subject – LCSH
Hemoglobin--Synthesis; Blood--Transfusion
Format
application/pdf
Genre/Form
masters theses
Language
English
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Recommended Citation
Sigurjonsson, Johann, "A Chemoenzymatic Approach to the Synthesis of Hemoglobin Oligomers" (2018). WWU Graduate School Collection. 750.
https://cedar.wwu.edu/wwuet/750