Lipoxygenase activity in rat dermis and epidermis: partial purification and characterization

Area of Science:

• Biochemistry
• Dermatology
• Enzymology

Background:

• Lipoxygenase (LOX) enzymes are crucial in metabolizing polyunsaturated fatty acids.
• LOX activity in skin tissues is implicated in various physiological and pathological processes.
• Understanding the specific LOX isoforms and their distribution in skin layers is essential.

Purpose of the Study:

• To characterize and localize lipoxygenase (LOX) activity within rat epidermal and dermal fractions.
• To identify the specific LOX isoforms present in different skin layers.
• To investigate the kinetic properties and inhibition patterns of skin LOX enzymes.

Main Methods:

• Enzyme isolation from rat dermis and epidermis using ammonium sulphate precipitation, hydrophobic chromatography, and gel filtration.
• Characterization of enzyme activity including molecular mass, isoelectric point (pI), and Michaelis constant (Km).
• Identification of LOX isoforms based on reaction products and inhibition by known LOX inhibitors.

Main Results:

• Lipoxygenase activity was detected in both microsomal and cytosolic fractions of rat epidermis and dermis.
• Dermal LOX activity (68 kDa, pI 4.6, Km 50 μM) showed characteristics of 15-LOX.
• Epidermal LOX activity (68 kDa, pI 4.6, Km 80 μM) exhibited properties of 12-LOX.

Conclusions:

• Rat skin contains distinct lipoxygenase activities in the epidermis (12-LOX) and dermis (15-LOX).
• These activities share similar molecular mass and pI, suggesting potential isoforms of a single enzyme or distinct enzymes.
• Further research is needed to elucidate whether one enzyme possesses dual regional specificities or if two separate enzymes are involved.