To determine if nitration of tyrosine residues by peroxynitrite (PN), which can be generated endogenously, can disrupt the phosphorylation of tyrosine residues in proteins involved in cell signaling networks, we studied the effect of PN-promoted nitration of tyrosine residues in a pentadecameric peptide, cdc2(6-20)NH2, on the ability of the peptide to be phosphorylated. cdc2(6-20)NH2 correspond...

The chemical origins of nitrated tyrosine residues (NT) formed in proteins during a variety of pathophysiological conditions remain controversial. Although numerous studies have concluded that NT is a signature for peroxynitrite (ONOO(-)) formation, other works suggest the primary involvement of peroxidases. Because metal homeostasis is often disrupted in conditions bearing NT, the role of meta...

The peroxidase-catalyzed nitration of tyrosine derivatives by nitrite and hydrogen peroxide has been studied in detail using the enzymes lactoperoxidase (LPO) from bovine milk and horseradish peroxidase (HRP). The results indicate the existence of two competing pathways, in which the nitrating species is either nitrogen dioxide or peroxynitrite. The first pathway involves one-electron oxidation...

nitration of potassium sulphamate was carried out using a mixture of sulphuric and nitric acid at -30 °c. the reaction time was optimized at the mole ratio of sulphuric to nitric acid of (1:3.5). the difference in product yield by changing the potassium to ammonium sulphamate was studied throughly. it was found that both the yield and purity of the product is better starting with potassium sulp...

Nitration of potassium sulphamate was carried out using a mixture of sulphuric and nitric acid at -30 °C. The reaction time was optimized at the mole ratio of sulphuric to nitric acid of (1:3.5). The difference in product yield by changing the potassium to ammonium sulphamate was studied throughly. It was found that both the yield and purity of the product is better starting with potassium ...

Nitration of tyrosine residues has been shown to be an important oxidative modification in proteins and has been suggested to play a role in several diseases such as atherosclerosis, asthma, lung and neurodegenerative diseases. Detection of nitrated proteins has been mainly based on the use of nitrotyrosine-specific antibodies. In contrast, only a small number of nitration sites in proteins hav...

Microwave irradiated palladium-catalyzed cross-coupling reaction of potassium styryltrifluoroborates and sodium nitrite gives the corresponding styryl nitrites in high yields. Potassium aryltrifluoroborates also furnish aryl nitrites under same reaction condition. This unprecedented cross-coupling is an interesting development and has the potential to lead to new nitration protocols.

In this work we have examined the nitration by acetyl nitrate of a range of activated and deactivated aromatic substrates in two ionic liquids and compared the results to the same reaction in dichloromethane. Both ionic liquids are stable to the reaction conditions, and in both ionic liquids the yields of reaction are higher after unit time than the same reactions in dichloromethane, although t...

The reaction of tetranitromethane with the tyrosine residues of the pituitary glycoprotein hormones, luteinizing hormone (LH) and thyroid-stimulating hormone (TSH) has been compared. The total reaction products were inactive if sufficient reagent was used. Although polymer formation is a major reaction, nitrated LH monomer was obtained which was then separated into its a and /3 subunits and a f...

A direct nitration of aromatic sulfonamides using sodium nitrite as the nitrating agent has been developed. The reaction shows typically mono-substitution selectivity and can be enlarged to the gram scale with good yield.