2026-09-21T08:05:24Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/70533 2023-07-11 col_2142_5131 col_2142_14795 com_2142_5130 com_2142_14794 com_2142_14793 com_2142_8903

Vollmer, Steven John 2014-12-15T23:43:47Z 2014-12-15T23:43:47Z 10000-01-01 1983 1983 The iron-sulfur prosthetic group of glutamine PRPP amidotransferase was found to be a {4Fe-4S} cluster. In the native enzyme, the cluster exists in the diamagnetic +2 redox state. Treatment of the cluster with oxidants resulted either in no reaction or in oxidative dissolution of the cluster, i.e., a +3 state was not detected. The cluster was reduced poorly with sodium dithionite, but was reduced readily by photoreduction with 5-deazaflavin. Photoreduction of the native enzyme resulted in formation of the +1 redox state of the cluster. The reduced enzyme was EPR silent. Examination of the reduced enzyme by Mossbauer spectroscopy indicated the presence of multiple unpaired electrons (S (GREATERTHEQ) 3/2). The E(,m) of the +1/+2 couple was determined to be (LESSTHEQ) -620 mV. The reduced enzyme was found to be active in the following assays: glutamine PRPP amidotransferase, glutaminase and PRPP hydrolase; these results demonstrated that the cluster does not have a redox function during catalysis of amide transfer by the enzyme. The glutamine utilizing site of the enzyme was examined through the use of the affinity ligand 6-diazo-5-oxo-L-norleucine. The thiolate of Cys-1 was identified as the enzyme nucleophile that hydrolyzes glutamine during amide transfer. The complete amino acid sequence of the enzyme is available, and the ligands to the iron-sulfur clusters have been tentatively identified: Cys-382, Cys-434, Cys-437 and Cys-440. Made available in DSpace on 2014-12-15T23:43:47Z (GMT). No. of bitstreams: 1 8410066.pdf: 8836683 bytes, checksum: 8b7b406dcafd62c497f715821d4ffb30 (MD5) Previous issue date: 1983 Embargo set by: Seth Robbins for item 70699 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 279 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983. http://hdl.handle.net/2142/70533 (UMI)AAI8410066 Chemistry, Biochemistry Glutamine Phosphoribosyl Pyrophosphate Amidotransferase From Bacillus Subtilis: Iron-Sulfur Biochemistry and Enzymology text Biochemistry Biochemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.