Rohini Sidhu

Date Approved

2010

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Chemistry

Committee Member

Steven Pernecky, Ph.D., Chair

Committee Member

Heather Holmes, Ph.D.

Committee Member

Deborah Heyl-Clegg, Ph. D.

Abstract

Cyclooxygenase (COX) metabolizes the polyunsaturated fatty acid arachidonic acid (AA) to PGG2, a cyclic endoperoxide that also contains a hydroperoxide, which is subsequently reduced to an alcohol in the enzyme to yield PGH2. Reactions catalyzed by COX-1 are significantly influenced by lipid hydroperoxides. The tyrosyl radical that abstracts the 13 pro(s) hydrogen from AA to initiate the COX catalytic cycle is generated by iron-oxo derivatives in the enzyme that result from lipid hydroperoxide interaction with heme iron. Commercial preparations of arachidonic acid (AA) contain lipid hydroperoxides that can be separated from AA by thin layer chromatography and readily reduced to alcohols using triphenylphosphine (TPP). The initial research objectives were to determine by GC-MS the effect of lipid hydroperoxides contained in AA preparations on COX-dependent metabolism of AA after TPP treatment and isolation of AA by TLC, and the effect of TTP treatment on the products formed during COX metabolism of AA. A novel metabolite was identified as a product of COX metabolism of AA in reactions where TPP was present; this product is a known chemo-tactic agent that influences immune function. The structural requirements of the reducing agent for production of the novel metabolite were subsequently investigated.

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