Date of Award

8-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Chemistry and Biochemistry

Thesis Sponsor/Dissertation Chair/Project Chair

Nina Goodey

Committee Member

David Konas

Committee Member

John Siekierka

Subject(s)

Phosphates, Ligand binding (Biochemistry), Tryptophan -- Synthesis

Abstract

Indole-3-glycerol phosphate synthase (IGPS) catalyzes the irreversible ring closure of 1-(ocarboxyphenylamino)- 1-deoxyribulose 5- phosphate (CdRP) into indole-3-glycerol phosphate (IGP) during the fourth step in tryptophan biosynthesis. Analysis of the crystal structure of IGPS from Mycobacterium tuberculosis (MtIGPS) hinted the importance of Lys119 for binding or catalysis. Lys110 from sulfolobus sulfataricus IGPS (ssIGPS) that aligns with Lys119 from MtIGPS, was proposed to be a general acid for the proton transfer that initiates the ring closure and decarboxylation of CdRP. To study the importance of Lys119 in the chemical mechanism for MtIGPS, an amino acid change was made at this position to study any changes in catalytic function or substrate binding affinity. Kinetic assays were performed and interesting, a mutation to alanine had a dramatic effect on the activity of MtIGPS. Our studies highlight the importance of Lys119 in the MtIGPS-catalyzed chemical mechanism.

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