Document Detail


Mechanisms and products of azo coupling in histochemical protease procedures based on primary aromatic amines as unspecific moieties.
MedLine Citation:
PMID:  2201736     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
It is presumed that the azo dyes generated by histochemical protease reactions are formed by substitution of a reactive aromatic carbon. They are referred to as dyes of the C-azo series. To confirm this assumption, the absorption spectra between 330 and 630 nm of azo dyes resulting from coupling between various aromatic amines of the aniline and naphthylamine series and the diazonium salts Fast Blue B and Fast Garnet GBC were studied in test tube experiments. Some of the amines were blocked by methylation to prevent coupling either at the amino group (N-methylated) or at the aromatic nucleus (C-methylated). Coupling was performed in buffered aqueous solutions of the diazonium salts. For analysis the azo dyes were dissolved in dimethylformamide. For acid rearrangement these solutions were acidified and incubated at elevated temperatures. After detection of dipeptidyl peptidase IV in tissue sections using Gly-Pro-4-methoxy-2-naphthylamine as substrate, the resulting dye was extracted and compared with the test tube compounds. All aromatic amines yielded azo dyes. Dyes extracted from sections and those test tube compounds derived from unmethylated or C-methylated amines showed almost identical spectral maxima, whereas dyes formed by N-methylated amines yielded different spectra. Acid rearrangement did not influence the spectral maxima of the N-methylated amine-derived dyes. Dyes resulting from C-methylated amines were destroyed. The results indicate that under histochemical conditions diazonium salts react primarily with the liberated free amino group but not with the aromatic nucleus of the unspecific moiety. Therefore, it is proposed that the formula of the final reaction product in naphthylamine-based protease histochemistry should be given as an N-azo dye, e.g., as a triazene.
Authors:
H G Frank
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society     Volume:  38     ISSN:  0022-1554     ISO Abbreviation:  J. Histochem. Cytochem.     Publication Date:  1990 Sep 
Date Detail:
Created Date:  1990-09-24     Completed Date:  1990-09-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9815334     Medline TA:  J Histochem Cytochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1295-300     Citation Subset:  IM    
Affiliation:
Department of Anatomy, Free University of Berlin, Federal Republic of Germany.
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MeSH Terms
Descriptor/Qualifier:
Amines / metabolism*
Aniline Compounds / metabolism
Animals
Azo Compounds / metabolism*
Diazonium Compounds / diagnostic use
Female
Histocytochemistry / methods*
Naphthalenes / metabolism
Peptide Hydrolases / diagnostic use*
Rats
Rats, Inbred Strains
Spectrophotometry
Temperature
Chemical
Reg. No./Substance:
0/Amines; 0/Aniline Compounds; 0/Azo Compounds; 0/Diazonium Compounds; 0/Naphthalenes; EC 3.4.-/Peptide Hydrolases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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