Histidine diazotized

Figure 4.33 Benzidine can be diazotized with sodium nitrite and HC1 for reaction with proteins through their tyrosine, histidine, or lysine side-chain groups.

Diazotization of proteins with diazonium-l/f-tetrazole in previous work has been studied in terms of reaction with histidine and tyrosine residues (50, 51). When E. coli pyrophosphatase was incubated with this reagent, there was pseudo-first-order inactivation, but analysis of the... 

Figure 151 Bis-diazotized tolidine can form cross-links with proteins through available tyrosine, histidine, or lysine residues.

Bis-diazotized benzidine can be used as a bridging reagent between proteins and haptens containing aromatic groups that react with diazon-ium compounds. A conjugate of thyrotropin-releasing hormone (which contains a reactive histidine residue) was obtained in this way. ... 

There are presently available several reagents, including diazotized io-dosulfanilic acid (ISA) and a Nal-lactoperoxidase (LPO) complex, that have been used to label cell membranes radioisotopically, presumably by labeling exposed tyrosine and/or histidine residues on plasma membrane proteins.Recently, the lactoperoxidase-catalyzed Nal reaction has... 

The coupling of diazotized /i-aminoacetophenone (DPAAP) with imidazole forms the basis of the differential pulse adsorption stripping voltammetry (DPASV) method for detection of histidine and its metabolites. The absorption of azo-histidine was found to obey Frumkin absorption isotherm <1999TAL319>. 

The Pauly test consists essentially of treating wool with diazotized sul-phanilic acid which couples with the tyrosine and histidine residues to form a brown-coloured product. These residues are found only in the cortex and, are absent from the cuticle so that the degree of staining is a measure of the breakdown of the scales. A modification of the Pauly test was recommended by Rimington J. Text. Inst., 1930, 21t, 237). The reagents required are ... 

The N-acetyl derivatives of tyrosine and histidine were purchased from Vega-Fox and diazotized by the method of Tabachnick and Sobotka (9). These reaction mixtures contained both mono- and bisdiazotized compounds which were separated by preparative TLC... 

It is interesting that when tyrosine is acylated with benzoyl chloride under this condition, it forms a dibenzoyl derivative that cannot react with the diazotized sulfanilic acid whereas histidine yields only a monobenzoyl derivative that can further react with diazonium acid. However, it has been found that when pyridine is added to scavenge the generated HCl, the reaction yield might be reduced." ... 

Concerning just what groups of proteins are diazotized, there appears to be some difference of opinion. Wiley and Lewis (320) state that casein treated with nitrous acid had lost some of its histidine, as determined by four different methods. Some of the tyrosine in the casein also appeared to have been affected. Eagle (318) suggested that f.r3rptophan is an im-... 

Tyrosine reacts, like histidine, with diazotized sulfanilic acid Pauly reagent). The coupled-... 

Diazotized arsanilic acid reacts with tyrosine and with histidine, lysine, tryptophan and arginine ... 

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