kovács reagent (isoamyl alcohol, para-dimethylaminobenzaldehyde concentrated hcl  (Thermo Fisher)

Journal: Microorganisms

Article Title: Tryptophanase Expressed by Salmonella Halts Breast Cancer Cell Growth In Vitro and Inhibits Production of Immunosuppressive Kynurenine

doi: 10.3390/microorganisms11051355

Figure Lengend Snippet: Detecting tryptophanase in transformed Salmonella . ( A ) Salmonella JR501 was directly transformed with the trytophanase operon ligation, colony lifted, and the filter paper soaked in rapid spot assay. Green (positive) colonies were rapidly visible. Note: the black spots represent guide marks for alignment with the original plate that were made with a needle dipped in India ink, which were used to align with the corresponding colonies. ( B ) Salmonella VNP20009 transformed with an empty pTrc99a (VNP20009-EV) vector (left) and the pTrc99a-tnaCAB (right) tested with Kovács reagent, showing a positive (fuchsia) color change.

Article Snippet: The 250 μL samples were mixed with an equal volume of Kovács reagent (isoamyl alcohol, para-dimethylaminobenzaldehyde and concentrated HCl; Remel) to generate a fuchsia-colored complex with para-dimethylaminobenzaldehyd.

Techniques: Transformation Assay, Ligation, Spot Test, Plasmid Preparation

Journal: Microorganisms

Article Title: Tryptophanase Expressed by Salmonella Halts Breast Cancer Cell Growth In Vitro and Inhibits Production of Immunosuppressive Kynurenine

doi: 10.3390/microorganisms11051355

Figure Lengend Snippet: Bacterial conversion of tryptophan to indole. VNP20009- tnaCAB (TNA) was compared with VNP20009 carrying the empty vector (EV + Gent) with and without treatment with 100 μg/mL gentamycin (Gent). ( A ) An indole standard curve from 0 to 100 μM read for absorbance at 570 nm. ( B ) A 60-min time course detecting conversion of tryptophan to indole using Kovács reagent and measuring absorbance at 570 nm.

Article Snippet: The 250 μL samples were mixed with an equal volume of Kovács reagent (isoamyl alcohol, para-dimethylaminobenzaldehyde and concentrated HCl; Remel) to generate a fuchsia-colored complex with para-dimethylaminobenzaldehyd.

Techniques: Plasmid Preparation

Journal: Microorganisms

Article Title: Tryptophanase Expressed by Salmonella Halts Breast Cancer Cell Growth In Vitro and Inhibits Production of Immunosuppressive Kynurenine

doi: 10.3390/microorganisms11051355

Figure Lengend Snippet: Separation of indole from tryptophan and measurement of tryptophan. ( A ) A tryptophan standard curve ranging from 1 to50 μM measured by absorbance at 218 nm. ( B ) Absorbance from 200 to 300 nm of 25 μM tryptophan. ( C ) Absorbance from 200 to 300 nm of 25 mm tryptophan. ( D ) Absorbance from 200 to 300 nm of 25 μM tryptophan plus 25 μm indole. ( E ) The reaction of Kovács reagent with 25 μM indole without (left) and with (right) prior extraction with chloroform. ( F ) Absorbance from 200 to 300 nm of 25 μM tryptophan extracted with chloroform. ( G ) Absorbance from 200 to 300 nm of 25 μM indole extracted with chloroform. ( H ) Absorbance from 200 to 300 nm of 25 μM tryptophan plus 25 μM indole extracted with chloroform.

Article Snippet: The 250 μL samples were mixed with an equal volume of Kovács reagent (isoamyl alcohol, para-dimethylaminobenzaldehyde and concentrated HCl; Remel) to generate a fuchsia-colored complex with para-dimethylaminobenzaldehyd.

Techniques: