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Repressible Operon: trp Operon01:21

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The trp operon in Escherichia coli exemplifies a repressible operon. It regulates the synthesis of tryptophan through repressor-mediated transcriptional control and attenuation. This dual regulatory mechanism ensures tryptophan biosynthesis occurs only when needed, conserving cellular resources.Structure of the trp OperonThe trp operon consists of five structural genes (trpE, trpD, trpC, trpB, and trpA) that encode enzymes for tryptophan biosynthesis. These genes are transcribed as a single...
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Related Experiment Video

Updated: May 3, 2026

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase
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Turning tryptophanase into odor-generating biosensors.

Yaqin Xu1, Zhuyuan Zhang, M Monsur Ali

  • 1Department of Chemical Engineering, McMaster University, Hamilton, Ontario, L8S 4L7 (Canada).

Angewandte Chemie (International Ed. in English)
|February 6, 2014
PubMed
Summary

A novel odor-based sensor system uses the enzyme tryptophanase (TPase) to detect molecules. This biosensor can identify antibodies and adenosine 5'-triphosphate (ATP) by generating detectable odors.

Keywords:
biosensorsmethyl mercaptanmolecular recognitionolfactory detectiontryptophanase

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Area of Science:

  • Biochemistry
  • Biosensor Technology
  • Analytical Chemistry

Background:

  • Enzyme-based detection systems offer high specificity.
  • Odor generation can serve as a sensitive reporting mechanism.
  • Tryptophanase (TPase) catalyzes reactions producing volatile compounds.

Purpose of the Study:

  • To develop a versatile odor-based sensor system utilizing tryptophanase (TPase).
  • To demonstrate the detection of antibodies and adenosine 5 omino-triphosphate (ATP) using the TPase system.
  • To establish a platform for broad molecular recognition via enzyme coupling.

Main Methods:

  • Biotinylation of TPase for conjugation with molecular recognition elements.
  • Development of an ELISA-like assay for antibody detection.
  • Coupled enzymatic assay with pyridoxal kinase (PKase) for ATP detection.

Main Results:

  • Detection of antibodies at nanomolar (nM) concentrations via odor.
  • Detection of adenosine 5 omino-triphosphate (ATP) at low micromolar (μM) concentrations.
  • Demonstration of a human-nose detectable odor generation system.

Conclusions:

  • The biotinylated TPase system provides a sensitive and adaptable platform for odor-based sensing.
  • This technology enables the detection of various analytes, including antibodies and ATP.
  • The system holds potential for diverse applications in molecular detection and diagnostics.