Subcellular fractionation of brown adipose tissue

Area of Science:

• Biochemistry
• Cell Biology
• Membrane Biology

Background:

• Brown adipose tissue (BAT) plays a key role in thermogenesis.
• Efficient isolation of plasma membranes is essential for studying BAT function.
• Current methods may lead to contamination or loss of membrane integrity.

Purpose of the Study:

• To develop a novel technique for preparing purified brown adipose tissue plasma membranes.
• To assess the purity and integrity of the isolated membranes.
• To investigate the impact of cell disruption methods on microsome integrity.

Main Methods:

• Utilized Metrizamide density gradient centrifugation for plasma membrane isolation.
• Prepared membranes from both crude mitochondria and crude microsome fractions.
• Assessed membrane purity using the marker enzyme 5'-nucleotidase.
• Evaluated microsome integrity via NADPH cytochrome c reductase activity.
• Compared cell disruption methods: liquid nitrogen grinding vs. homogenization.

Main Results:

• Metrizamide technique successfully isolated plasma membranes with high 5'-nucleotidase specific activity (15 +/- 3 and 14 +/- 2).
• Plasma membranes derived from microsomes showed minimal mitochondrial contamination.
• Liquid nitrogen grinding significantly enhanced microsome integrity, yielding 3.5 times greater NADPH cytochrome c reductase specific activity compared to homogenization.

Conclusions:

• Metrizamide offers an effective method for purifying brown adipose tissue plasma membranes.
• Microsome integrity is highly dependent on the cell disruption technique employed.
• Optimized cell disruption, like liquid nitrogen grinding, is crucial for preserving cellular components during isolation.