Laser Induced Autofluorescence in the Monitoring of b-Mercaptoethanol Mediated Photo Induced Proton Coupled Electron Transfer in Proteins

Manjunath, S and Rao, Satish BS and Satyamoorthy, K and Mahato, KK (2015) Laser Induced Autofluorescence in the Monitoring of b-Mercaptoethanol Mediated Photo Induced Proton Coupled Electron Transfer in Proteins. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 149. pp. 607-614. ISSN 1386-1425

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Abstract

Photo induced proton coupled electron transfer (PCET) is an important process that many organisms use for progression of catalytic reactions leading to energy conversion. In the present study, the influence of SDS and BME on the redox properties of tyrosine and tryptophan for five different globular proteins, BSA,HSA, RNase-A, trypsin and lysozyme were studied using laser induced autofluorescence. The proteins were subjected to denaturation under SDS, SDS plus heat and SDS plus b-mercaptoethanol (BME) plus heat and the corresponding fluorescence were recorded. The influence of BME on the autofluorescence properties of the proteins were evaluated upon tris-2-corboxy-ethyl phosphine (TCEP) denaturation.The BSA and HSA when exposed to SDS alone, exhibited hydrophobic collapse around their tryptophan moieties. However, these proteins when treated with SDS plus BME plus heat, an unusual red shift in the emission was observed, may be due to proton transfer from hydroxyl group of the excited tyrosine residues to the local microenvironments. The observation was further confirmed with similar proton transfer in absence of tryptophan in RNase-A showing involvement of tyrosine in the process. A drastic quenching of fluorescence in all of the proteins under study were also observed, may be due to photo-induced electron transfer (PET) from BME to the intrinsic fluorophores resulting in radical ions formation,evaluated upon DCFDA measurements.

Item Type: Article
Uncontrolled Keywords: Photo-induced electron transfer (PET); Sodium dodecyl sulfate (SDS); Betamercapto ethanol (BME); Tris-2-corboxy-ethyl phosphine (TCEP); Fluorescence emission-shift
Subjects: Life Sciences > MLSC Manipal
Depositing User: KMC Library
Date Deposited: 26 Sep 2015 09:12
Last Modified: 26 Sep 2015 09:12
URI: http://eprints.manipal.edu/id/eprint/144157

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