Premium
β‐oxidation enzymes and the carnitine‐dependent oxidation of palmitate and palmitoyl CoA in mitochondria from avocado
Author(s) -
MASTERSON C.,
WOOD C.,
THOMAS D. R.
Publication year - 1992
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1992.tb00979.x
Subject(s) - biochemistry , mitochondrion , carnitine , beta oxidation , mitochondrial matrix , catalase , microbody , peroxisome , enzyme , chemistry , organelle , biology , cytosol , gene
Two sites for the β‐oxidation of fatty acids in avocado ( Persea americana L.) mesocarp exist. One site is the microbody, the other the mitochondrion. It is apparent that the mitochondrial membrane barrier, which remains intact after sucrose density gradient centrifugation, prevents rapid access of acyl CoA substrates to matrix β‐oxidation sites. Thus, intact mitochondria showed little β‐oxidation enzyme activity. Rupturing of the mitochondrial membrane allowed rapid access of the acyl CoA substrates to matrix sites. Consequently, in ruptured mitochondria, high O 2 ‐oxidation enzyme activities were measured. O 2 uptake studies further distinguished the two organellar sites of β‐oxidation. During palmitoyl CoA oxidation, O 2 uptake was reduced by catalase and increased by KCN in the microbodies, whilst mitochondrial O 2 uptake was unaffected by catalase and reduced by KCN. This reflected the differing fates of FADH 2 , produced during the first β‐oxidation step, in the two organelles. In addition, only the mitochondrial β‐oxidation of fatty acids was carnitine‐dependent.