Glyoxysomes are specializedperoxisomes found inplants (particularly in thefat storage tissues ofgerminating seeds) and also in filamentous fungi. Seeds that contain fats and oils include corn, soybean, sunflower, peanut and pumpkin.[1] As in all peroxisomes, in glyoxysomes the fatty acids are oxidized toacetyl-CoA by peroxisomal β-oxidation enzymes. When the fatty acids are oxidized hydrogen peroxide (H2O2) is produced as oxygen (O2) is consumed.[1] Thus the seeds need oxygen to germinate. Besides peroxisomal functions, glyoxysomes possess additionally the key enzymes of theglyoxylate cycle (isocitrate lyase andmalate synthase) which accomplish theglyoxylate cycle bypass.[2]
Thus, glyoxysomes (as all peroxisomes) containenzymes that initiate the breakdown offatty acids and additionally possess the enzymes to produce intermediate products for the synthesis ofsugars bygluconeogenesis. The seedling uses these sugars synthesized from fats until it is mature enough to produce them byphotosynthesis.
Plant peroxisomes also participate inphotorespiration and nitrogen metabolism in root nodules.