Browsing by Author "Luthuli, Duncan Sifiso"

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    Analysis of the effects of Gold nanoparticles on the functional integrity of select serum proteins and heat shock proteins of mammalian origin
    (2012) Luthuli, Duncan Sifiso; Shonhai, A.; Revaprasadu, N.
    Gold nanoparticles (AuNPs) are a natural starting point for understanding nanoparticle-protein interaction due to their possible applications in biomedical functions, such as disease diagnosis and drug delivery. This has driven interest to understand the effects of AuNPs on the functional and structural integrity of heat shock proteins (Hsp) and serum proteins. When AuNPs are used for medical purposes through the intravenous route, they may be modified by serum proteins and these modifications may give rise to pathologies, or alter the intended purpose of the nanoparticle. Furthermore, Hsp are ubiquitous proteins that occur in cells and are upregulated under stress. It is envisaged that Hsp may also interact with AuNPs delivered to cells and/or the blood circulatory system. In this study, I sought to analyse the interaction between AuNPs and bovine serum albumin (BSA), citrate synthase (CS), malate dehydrogenase (MDH) as well as human heat shock protein 70 (Hhsp70). AuNPs were synthesised by a citrate reduction method in the presence of cysteine as the capping agent, and analysed using UV/visible spectroscopy and transmission electron microscopy (TEM). The effects of AuNPs on the stability of BSA, MDH, Hhsp70 and CS to heat stress were assessed spectroscopically, both in the presence and absence of AuNPs. I further investigated the effects of AuNPs on the function of Hhsp70 in suppressing the aggregation of MDH. Data observed in this study suggested that, the interaction between AuNPs and proteins (BSA and Hhsp70) may be facilitated by sulfhydryl (SH) groups present in them. It was also observed that AuNPs have capabilities of suppressing heat induced aggregation of MDH and CS. Thus AuNPs have chaperone activity as they are capable of maintaining proteins in their soluble, functional forms during heat stress.