Event Title

Protein Photo-oxidation: The Effects of Singlet Oxygen on Protein Function

Location

CSU Ballroom

Start Date

20-4-2015 10:00 AM

End Date

20-4-2015 11:30 AM

Student's Major

Chemistry and Geology

Student's College

Science, Engineering and Technology

Mentor's Name

John Thoemke

Mentor's Email Address

john.thoemke@mnsu.edu

Mentor's Department

Chemistry and Geology

Mentor's College

Science, Engineering and Technology

Description

Proteins are known to be major targets for photo-oxidation due to their high abundance in biological systems. Photo-oxidation occurs via several channels, including reactions between singlet oxygen and tryptophan, tyrosine, histidine, methionine, or cysteine residues. In previous studies, reaction rates of singlet oxygen with particular residues have been measured at variable positions within a single protein and comparing proteins with reactive residues having varying degrees of accessibility. These studies suggest that amino acid residues completely buried within a protein have small rate constants compared to residues located closer to the surface. In this study, the effects on protein functionality (assessed by enzyme activity assays) of singlet oxygen reacting with variably accessible residues were determined. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lysozyme contain, respectively, histidine and tryptophan residues with varying singlet oxygen accessibility surface areas (1O2-ASA) as determined using standard computational methods. Reaction rates between singlet oxygen and the proteins were determined via competitive kinetics with furfuryl alcohol, a singlet oxygen molecular probe. The reaction rates were then correlated to functional effects found from GAPDH and lysozyme enzyme activity assays. The results tested the hypothesis of a protein “defense mechanism”, whereby proteins having a greater number of surface residues, such as GAPDH, retain their function better than proteins having fewer accessible photooxidizable residues, like lysozyme.

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Apr 20th, 10:00 AM Apr 20th, 11:30 AM

Protein Photo-oxidation: The Effects of Singlet Oxygen on Protein Function

CSU Ballroom

Proteins are known to be major targets for photo-oxidation due to their high abundance in biological systems. Photo-oxidation occurs via several channels, including reactions between singlet oxygen and tryptophan, tyrosine, histidine, methionine, or cysteine residues. In previous studies, reaction rates of singlet oxygen with particular residues have been measured at variable positions within a single protein and comparing proteins with reactive residues having varying degrees of accessibility. These studies suggest that amino acid residues completely buried within a protein have small rate constants compared to residues located closer to the surface. In this study, the effects on protein functionality (assessed by enzyme activity assays) of singlet oxygen reacting with variably accessible residues were determined. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lysozyme contain, respectively, histidine and tryptophan residues with varying singlet oxygen accessibility surface areas (1O2-ASA) as determined using standard computational methods. Reaction rates between singlet oxygen and the proteins were determined via competitive kinetics with furfuryl alcohol, a singlet oxygen molecular probe. The reaction rates were then correlated to functional effects found from GAPDH and lysozyme enzyme activity assays. The results tested the hypothesis of a protein “defense mechanism”, whereby proteins having a greater number of surface residues, such as GAPDH, retain their function better than proteins having fewer accessible photooxidizable residues, like lysozyme.

Recommended Citation

Eatwell, Maegan. "Protein Photo-oxidation: The Effects of Singlet Oxygen on Protein Function." Undergraduate Research Symposium, Mankato, MN, April 20, 2015.
http://cornerstone.lib.mnsu.edu/urs/2015/poster_session_A/30