Biochemical and Molecular Characterization of a Novel Cu/Zn Superoxide Dismutase from Amaranthus hypochondriacus L.: an Intrinsically Disordered Protein

Abstract

A novel Cu/ZnSOD from Amaranthus hypochondriacus was cloned, expressed, and characterized. Nucleotide sequence analysis showed an open reading frame (ORF) of 456 bp, which was predicted to encode a 15.6-kDa molecular weight protein with a pI of 5.4. Structural analysis showed highly conserved amino acid residues involved in Cu/Zn binding. Recombinant amaranth superoxide dismutase (rAhSOD) displayed more than 50 % of catalytic activity after incubation at 100 °C for 30 min. In silico analysis of Amaranthus hypochondriacus SOD (AhSOD) amino acid sequence for globularity and disorder suggested that this protein is mainly disordered; this was confirmed by circular dichroism, which showed the lack of secondary structure. Intrinsic fluorescence studies showed that rAhSOD undergoes conformational changes in two steps by the presence of Cu/Zn, which indicates the presence of two binding sites displaying different affinities for metals ions. Our results show that AhSOD could be classified as an intrinsically disordered protein (IDP) that is folded when metals are bound and with high thermal stability.

Proteomic response of Saccharomyces boulardii to simulated gastrointestinal conditions and encapsulation

“…Superoxide dismutases (SODs, EC 1.15.1.1) maintain Reactive Oxygen Species (ROS) balance by converting O 2 into hydrogen peroxide (H 2 O 2 ); SODs are classified essentially by the metal cofactors in three known types: manganese (MnSOD), copper/zinc (Cu-ZnSOD),) and iron (FeSOD) which are localized in different cellular compartments. In eukaryotic cells, MnSOD is found in the mitochondria and peroxisomes, whereas Cu/ZnSOD isoenzymes are found in cytosolic space and in chloroplasts of higher plants, while FeSOD isoenzymes are usually associated to chloroplast when present in plants (Montero-Morán et al, 2015). It is widely known that oxidative stress results from other stressing conditions such as starvation, lack of nitrogen or glucose, and hypoxia (Kroll et al, 2014).…”