In vitro dioxygenase activity characterization using headspace stir bar sorptive extraction (HSSE)

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• Carotenoid cleavage enzymes (CCDs) produce volatile apocarotenoids.
• Understanding CCD activity is crucial for various biological processes.
• Existing methods for analyzing CCD products are often complex and time-consuming.

Purpose of the Study:

• To develop a sensitive and efficient analytical method for determining apocarotenoid volatiles.
• To characterize the enzymatic activity of the gardenia CCD4a (GjCCD4a) enzyme in E. coli.
• To establish optimal conditions for analyzing CCD-mediated cleavage products.

Main Methods:

• Headspace sorptive extraction (HSSE) coupled with gas chromatography-mass spectrometry (GC-MS).
• Utilized recombinant GjCCD4a enzyme in E. coli engineered to produce β-carotene.
• Optimized headspace conditions and induction periods for protein expression.

Main Results:

• Successfully developed and validated the HSSE-GC-MS method for apocarotenoid determination.
• Achieved excellent linearity (R² > 0.95) and sensitive detection limits for β-cyclocitral.
• Demonstrated reduced sample handling complexity and processing time compared to liquid chromatography.

Conclusions:

• The HSSE-GC-MS method offers an efficient and sensitive approach for apocarotenoid analysis.
• This method facilitates the study of CCD enzymatic processes in bacterial systems.
• The developed technique simplifies the detection of cleavage products and CCD activity determination.