Characterization of UPF peptides, members of the glutathione analogues library, on the basis of their effects on oxidative stress-related enzymes

Abstract

Previously the authors have designed and synthesized a library of antioxidative glutathione analogues called UPF peptides which are superior to glutathione in hydroxyl radical elimination. This paper is a follow-up study which investigated the effects of the most promising members of the library (UPF1 and UPF17) on oxidative stress-related enzymes. At concentrations used in vivo experiments neither UPF peptide influenced the activity of glutathione peroxidase (GPx) when purified enzyme or erythrocyte lysate was used. At higher concentrations they inhibited GPx activity. UPF peptides had no effect on glutathione reductase (GR) activity. Also they, as well as glutathione itself, slightly increased MnSOD activity in human brain mitochondria and inhibited oxidative burst caused by neutrophil NAD(P)H oxidase. RT-PCR measurements showed that UPF1 and UPF17 have no effect on GPx and MnSOD expression level in human blood mononuclear cells. The results of this study confirm that investigated UPF peptides do not interfere with the enzymatic mechanisms of antioxidative defence and can be used as themselves or as a lead for the protector molecule design against excessive oxidative stress.

Glutathione metabolism and Parkinson's disease

“…These compounds link GSH molecules to tyrosine derivatives by an amide bond and have better hydroxyl radical scavenging properties than glutathione alone. Two of these UPF proteins, UPF1 (4-methoxy-L-tyrosinyl- γ -L-glutamyl-L-cysteinyl-glycine) and UPF17 (4-methoxy-L-tyrosinyl- α -L-glutamyl-L-cysteinyl-glycine) are shown to increase free radical scavenging by 500-fold [252]. UPF1 is resistant to γGT activity and increased CuZnSOD activity, suggesting that UPF1 has antioxidant activity independent from GSH [253].…”

Effect of a Fusion Peptide by Covalent Conjugation of a Mitochondrial Cell-Penetrating Peptide and a Glutathione Analog Peptide

“…Surprisingly, the covalent conjugation of the mitochondrial peptide to the GSH analog resulted in a more efficient antioxidant CPP, suggesting that both the OH and SH groups are involved in radical depletion reactions. This has been previously investigated by Ehrlich et al., 29 where the Cys residue in the sequence was replaced with a Ser residue in the UPF26 sequence, and reduction of the hydroxyl radical scavenging ability was not observed. These analogs showed EC 50 values of the scavenging reaction in the submicromolar range (the EC 50 for UPF25 was approximately 30 nM) 30 …”

Diverse Effects of Glutathione and UPF Peptides on Antioxidant Defense System in Human Erythroleukemia Cells K562

“…However, the γ -glutamyl moiety containing UPF1 needed more time for MnSOD activation compared to UPF17, which had the effect already after 5 min incubation. UPF1 and UPF17 have also different influence on glutathione peroxidase activity (GPx): at higher concentrations than used in in vivo experiments, both UPF1 and UPF17 inhibited activity concentration dependently whereas the α -peptide bond containing UPF17 had stronger inhibitory effect [22]. In the present work we investigated how the replacement of γ -peptide bond with α -peptide bond on GSH and its analogue UPF1 affects CuZnSOD activity and level of GSH in K562 cells.…”