Structure and Reactivity Studies of a Synthetic Model System for a Rare Earth Metal−Containing Enzyme / Alison L Knasin.

Format:

Book

Thesis/Dissertation

Author/Creator:

Knasin, Alison L., author.

Contributor:

University of Pennsylvania. Chemistry, degree granting institution.

Language:

English

Subjects (All):

Inorganic chemistry.

Materials science.

Biochemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Local Subjects:

Inorganic chemistry.

Materials science.

Biochemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Physical Description:

1 online resource (463 pages)

Distribution:

Ann Arbor : ProQuest Dissertations & Theses, 2023

Contained In:

Dissertations Abstracts International 85-08B.

Place of Publication:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2022.

Language Note:

English

Summary:

The rare earth elements (La−Lu, Sc, and Y) were recently determined to have a biological role in bacteria and were discovered bound to a redox−active cofactor within the active site of a methanol dehydrogenase enzyme. The enzyme catalyzes the oxidation of methanol to formaldehyde. Since this discovery, it has been of interest to understand the mechanism by which these enzymes operate, as well as the reasons that these enzymes show preferential uptake for rare earth cations over calcium. Previous work by our group included synthesis and characterization of a redox−active ligand that, when coordinated to the La3+ cation, was capable of serving as a model of the active site of rare earth−dependent methanol dehydrogenase. This dissertation describes further work on the development of a series of the rare earth metal−dependent biomimetic complexes to explore the active site of these enzymes, and the mechanism by which the protein is able to dehydrogenate alcohols. The series of complexes includes the ligand LQQ coordinated to the rare earth cations (La3+, Nd3+, and Eu3+), as well as initial results with Ca2+ and Y3+. Several examples of the rare earth complexes were characterized with the ligand present in different redox states. The dehydrogenation abilities of these complexes towards alcohols were studied, both stoichiometrically and catalytically, and a kinetic isotope effect study was performed. The results obtained with 4−methylbenzyl alcohol and the model system showed that catalytic ability of the complexes increased when coordinated to earlier, rather than later, rare earth elements, with complex reactivity decreasing with increased Lewis acidity of the bound metal cation. In Nature, enzyme activity increases with increasing Lewis acidity between La3+ and Nd3+, then decreases due to other competing factors. The model compounds faithfully reproduce the overall trend of reactivity observed for the enzyme, albeit with subtle differences observed for the early metals. Moreover, the models afforded additional mechanistic details that expand on fundamental knowledge for the first rare earth−dependent biological system.

Notes:

Source: Dissertations Abstracts International, Volume: 85-08, Section: B.

Advisors: Schelter, Eric J.; Committee members: Dmochowski, Ivan J.; Berry, Donald H.; Goldberg, Karen I.

Department: Chemistry.

Ph.D. University of Pennsylvania 2023.

Local Notes:

School code: 0175

ISBN:

9798381510812

Access Restriction:

Restricted for use by site license.