Delta-6-desaturation of linoleic and alpha-linolenic acids in aged rats: a kinetic analysis.
Kinetic parameters of the delta-6-desaturation reaction were determined using both cis-linoleic and alpha-linolenic acid as substrates in liver microsomes of rats of different ages. The Km value for delta-6-desaturation of linoleic acid increased proportionally to the animal age, while the Vm did not change until 25 months of age. The Km values for alpha-linolenic acid were similar in young and senescent rats; on the contrary there was a significant aging influence on the Vm values. The affinity of the enzyme for the (n-3) series substrate was not so influenced by aging as the affinity for the (n-6) series substrate. This loss of affinity may be a key factor in aging through altering the polyunsaturated fatty acid content and distribution into cellular phospholipids.
Hrelia
S
S
Dipartimento di Biochemica, Centro Ricerche sulla Nutrizione (Dip. Biochimica), Bologna, Italy.
Celadon
M
M
Rossi
C A
CA
Biagi
P L
PL
Bordoni
A
A
D000375:Aging / Q000378:metabolism*; D000818:Animals; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D007700:Kinetics; D008041:Linoleic Acids / Q000378:metabolism*; D008042:Linolenic Acids / Q000378:metabolism*; D050602:Linoleoyl-CoA Desaturase; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
D008041:Linoleic Acids; D008042:Linolenic Acids; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase