Oxidative Products of Peptides Due to Interaction with Peroxyl Radicals

2021 ◽  
Author(s):  
Ramak Esfandi ◽  
Apollinaire Tsopmo
Keyword(s):  
Peroxyl Radicals ◽  
Oxidative Products

Isomerization of the Isoprene Hydroxy Nitrates and Formation of Orthonitrite Compounds

2019 ◽  
Author(s):  
Gabriel da Silva
Keyword(s):  
Hydroxy Group ◽  
Peroxyl Radical ◽  
Branching Fractions ◽  
Membered Ring ◽  
Low Energy ◽  
Peroxyl Radicals ◽  
Aerosol Formation ◽  
Subsequent Removal ◽  
Ring Compounds ◽  
Group Migration

Atmospheric oxidation of isoprene produces significant yields of eight unique nitrate 11 compounds, each with a β- or δ-hydroxy group. These isoprene hydroxy nitrates (ISOPNs) 12 significantly impact upon global NOx budgets, O3 levels, and aerosol formation. 13 Uncertainties exist, however, in our understanding of ISOPN chemistry, particularly in their 14 yields from the reaction of isoprene peroxyl radicals with NO. This study describes novel 15 isomerization reactions of the ISOPNs, identified through the application of computational 16 chemistry techniques. These reactions produce saturated polycyclic orthonitrite compounds 17 via attack of the R–NO2 group on the vinyl moiety. For the δ-hydroxy nitrates, low-energy 18 isomerization pathways exist to six-membered ring compounds that are around 5 kcal mol-1 19 exothermic. These reactions proceed with barriers around 15 kcal mol-1 below the 20 respective peroxyl radical + NO reactants and yield orthonitrites that can further isomerize 21 to β-hydroxy ISOPNs. Moreover, the δ-hydroxy nitrates can directly interconvert with their β 22 substituted counterparts via NO3 group migration, with barriers that are lower yet. It follows 23 that β-hydroxy nitrates may be stabilized in the δ-hydroxy form, and vice versa. Moreover, 24 the lowest-energy pathway for dissociation of the δ-hydroxy ISOPNs is for the formation of 25 β-hydroxy alkoxyl radicals, and because of this established branching fractions between the 26 various isoprene peroxyl radicals may require re-evaluation. The results presented here also 27 suggest that ISOPNs may be stabilized to some extent in their saturated orthonitrite forms, 28 which has implications for both the total nitrate yield and for their subsequent removal by 29 OH, O3, and photolysis.<br><br>

Effect of MTGase on silver carp myofibrillar protein gelation behavior after peroxidation induced by peroxyl radicals

2021 ◽  
Vol 349 ◽  
pp. 129066
Author(s):  
Shan Qian ◽  
Peipei Dou ◽  
Junlan Wang ◽  
Lin Chen ◽  
Xinglian Xu ◽  
...  
Keyword(s):  
Silver Carp ◽  
Myofibrillar Protein ◽  
Peroxyl Radicals ◽  
Protein Gelation ◽  
Gelation Behavior

Effects of oxidative modification of peroxyl radicals on the structure and foamability of chickpea protein isolates

2021 ◽  
Vol 86 (3) ◽  
pp. 824-833
Author(s):  
Zengfang Zhu ◽  
Xiaoying Mao ◽  
Qingzhi Wu ◽  
Jian Zhang ◽  
Xiaorong Deng
Keyword(s):  
Oxidative Modification ◽  
Peroxyl Radicals ◽  
Protein Isolates

Purpurogallin is a more powerful protector of kidney cells than Trolox and allopurinol

1992 ◽  
Vol 70 (8) ◽  
pp. 684-690 ◽  
Author(s):  
Ling-Hua Zeng ◽  
Tai-Wing Wu
Keyword(s):  
Xanthine Oxidase ◽  
Phase Contrast ◽  
Potent Inhibitor ◽  
Rat Kidney ◽  
Peroxyl Radicals ◽  
Kidney Cells ◽  
Tubular Epithelial Cells ◽  
Electron Microscopic ◽  
Oxidase Inhibition ◽  
Xanthine Oxidase Inhibition

Phase contrast and electron microscopic experiments demonstrated that oxyradicals generated with xanthine oxidase and hypoxanthine markedly damage rat kidney mesangial and porcine tubular epithelial cells. Purpurogallin, a phenol found in oak nutgalls, prolongs survival of the xanthine oxidase exposed renal cells three- to nine-fold longer than those without purpurogallin present. At levels equimolar to purpurogallin, either Trolox or allopurinol is less effective in delaying cell necrosis. Purpurogallin scavenges not only xanthine oxidase generated oxyradicals, but also non-enzymatically produced peroxyl radicals, more actively than equimolar levels of Trolox or allopurinol. Purpurogallin inhibits xanthine oxidase with severalfold higher potency than allopurinol and its more active metabolite oxypurinol. Therefore, purpurogallin is a stronger antioxidant than Trolox and a more potent inhibitor of xanthine oxidase than allopurinol as well as oxypurinol.Key words: purpurogallin, kidney cells, oxyradical damage, xanthine oxidase inhibition, antioxidant.

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