The structural and functional analysis of peroxiredoxin 6 and glutathione transferase P1-1

• Main Author: Molaudzi, Zanele
• Format: Others
• Language: en
• Published: 2018
• Subjects: Peroxiredoxins; Glutathione transferase
• Online Access: Molaudzi, Zanele (2017) The structural and functional analysis of peroxiredoxin 6 and glutathione transferase P1-1, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/25004>; https://hdl.handle.net/10539/25004

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017. === Glutathione transferase P1-1 (GSTP1-1) is an enzyme belonging to the glutathione transferases superfamily of enzymes responsible for xenobiotic detoxification metabolism in the cells. It has been shown recently that GSTP1-1 performs a distinct function from its family members in that it acts as a carrier of the glutathione in the reactivation and glutathionylation of oxidised peroxiredoxin 6 (Prdx6). Prdx6 is a peroxidase belonging to the peroxiredoxin superfamily. The family functions to reduce organic peroxides which are sources of oxidative stress. Prdx6, however, differs from its family members as it is a bi-functional enzyme and it only contains one cysteine in its catalytic centre. The interaction of GSTP1-1 with Prdx6 has proven to be vital for the functioning of the Prdx6. The recombinant Prdx6 and GSTP1-1 proteins have been over-expressed and purified to homogeneity. The secondary structure of the proteins was studied using circular dichroism which has shown that GSTP1-1 is predominantly alpha helical and Prdx6 is mainly alpha helical with aspects of a beta sheet. The tertiary structural analysis has been carried out using tryptophan fluorescence which revealed that in both proteins the tryptophans are partially exposed to solvent. Furthermore, the quaternary structure was analysed using size exclusion-HPLC which indicated that the proteins are homodimeric in solution (both ~50 kDa). This study will present the findings on the overall characterisation and the implications of the findings on the interaction of these proteins. === LG2018