© 1999 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999

8.5.3.9 Peroxisomes

Peroxisomes (also called microbodies)¹⁰⁰⁰ are rough ER-budded organelles typically 0.1-1 microns in diameter.⁵³¹ Peroxisomes occur in most cells, but are most prominent in liver and kidney cells which are active in detoxification. The organelle destroys cytotoxic chemicals such as hydrogen peroxide, methanol, ethanol, formate, formaldehyde, nitrites and phenols, as well as D-amino acids which are not found in proteins and are not recognized by enzymes involved in the degradation of the more common L-amino acids. Peroxisomes also catalyze 25-50% of all fatty acid breakdown in cells (the remainder occurs in the mitochondria). The organelle is a concentrated source of three oxidative enzymes found in liver cells -- D-amino acid oxidase, urate oxidase (usually present in a distinctive crystalline core), and catalase (which is up to 40% of total peroxisomal protein and most of the catalase present in a cell).

Peroxisomes may also protect cells from toxic oxygen levels,^3069-3072 since peroxisomal O₂ consumption is directly proportional to cellular oxygen concentration,⁹³⁹ unlike mitochondrial respiration. In case of excessive O₂ levels, peroxisomal respiration is greatly stimulated, reducing the intracellular oxygen tension.

Last updated on 20 February 2003