ABSTRACT
Three potential chromogenic enzymatic probes, each possessing a self-immolative spacer unit, were synthesised for the purpose of detecting l-alanylaminopeptidase activity in microorganisms. An Alizarin-based probe was the most effective, allowing several species to generate strongly coloured colonies in the presence of metal ions.
Subject(s)
Anthraquinones/chemistry , CD13 Antigens/metabolism , Chromogenic Compounds/chemistry , Anthraquinones/metabolism , Chromogenic Compounds/metabolism , Gram-Negative Bacteria/enzymology , Gram-Negative Bacteria/growth & development , Gram-Positive Bacteria/enzymology , Gram-Positive Bacteria/growth & development , Metals/chemistry , Substrate SpecificityABSTRACT
A series of fluorogenic enzymatic substrates that incorporate a self-immolative spacer were synthesised for the purpose of identifying l-alanylaminopeptidase activity in microorganisms in agar media. These substrates resulted in the generation of fluorescent microorganism colonies with Gram-negative microorganisms.
Subject(s)
Bacteria/enzymology , CD13 Antigens/metabolism , Enzyme Assays/methods , Fluorescent Dyes/metabolism , Yeasts/enzymology , CD13 Antigens/analysis , Fluorescent Dyes/analysis , Humans , Substrate SpecificityABSTRACT
A series of amino acid derivatives 8-10, 42 and 43 have been prepared as chromogenic enzyme substrates in order to detect aminopeptidase activity in clinically important Gram-negative and Gram-positive bacteria. Enzymatic hydrolysis liberates the amino acid moiety and either a 4-aminophenol or a 4-dialkylaminoaniline derivative which undergoes oxidative coupling with 1-naphthol or a substituted 1-naphthol giving an indophenol dye. Substrates and 1-naphthols were incorporated into an agar-based culture medium and this allowed growth of intensely coloured bacterial colonies based on hydrolysis by specific enzymes. Red/pink coloured colonies were produced by the substrates 8-10 and blue coloured colonies were formed by the substrates 42 and 43. The L-alanyl aminopeptidase substrates 8 targeted L-alanyl aminopeptidase activity and gave coloured colonies with a range of Gram-negative bacteria. Substrates 9 targeted ß-alanyl aminopeptidase activity and generated coloured colonies with selected Gram-negative species including Pseudomonas aeruginosa. Three substrates for L-pyroglutamyl acid aminopeptidase (10a, 10c and 43) were hydrolysed by enterococci and Streptococcus pyogenes to generate coloured colonies. Two yeasts were also included in the study, but they did not produce coloured colonies with any of the substrates examined.
