[Rapid spectrophotometric method for determining ornithine decarboxylase using 2,4-dinitrofluorobenzene]

Area of Science:

• Biochemistry
• Enzymology
• Spectrophotometry

Background:

• Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis.
• Altered ODC activity is implicated in tissue regeneration and cancer development.
• Accurate quantification of ODC activity is crucial for understanding these processes.

Purpose of the Study:

• To develop a sensitive and reproducible spectrophotometric micromethod for quantifying ornithine decarboxylase (ODC) activity.
• To assess ODC activity in various animal tissue types, including normal, regenerating, and malignant liver tissues.

Main Methods:

• Development of a spectrophotometric assay for ornithine decarboxylase (ODC) activity.
• Measurement of ODC activity in homogenates of control, regenerating, and malignant liver tissues, including specific hepatomas (G-27, G-46).
• Determination of assay linearity, pH optimum, recovery, sensitivity, and reproducibility.

Main Results:

• A linear relationship was established between optical density and dinitrophenyl putrescine concentration (0-150 nmol/sample).
• The ODC pH optimum was identified between pH 6.4-6.8, independent of the buffer used.
• Significantly elevated ODC activity was observed in regenerating liver, malignant liver tissues, and hepatomas G-27 and G-46 compared to controls.

Conclusions:

• The developed spectrophotometric micromethod is sensitive, reproducible, and accurate for estimating ornithine decarboxylase (ODC) activity.
• The method demonstrates increased ODC activity in pathological liver conditions, highlighting its potential diagnostic value.
• This assay provides a reliable tool for biochemical research and clinical diagnostics involving ODC.