Gw. Power et al., INFLUENCE OF DIET ON THE KINETIC-BEHAVIOR OF HEPATIC CARNITINE PALMITOYLTRANSFERASE-I TOWARD DIFFERENT ACYL COA ESTERS, Lipids, 32(1), 1997, pp. 31-37
The influence of diet on the kinetics of the overt form of rat liver m
itochondrial carnitine palmitoyltransferase (CPT I; EC 2.3.1.21) was s
tudied using rats fed either a low-fat diet (3% w/w fat), or diets whi
ch were supplemented with either olive oil (OO), safflower oil (SO) or
menhaden (fish) oil (MO) to 20% w/w of fat (high fat diets). When ani
mals were fed each of these four diets for 10 days, the order of the a
pparent maximal activity (v(max)) of CPT I toward various individual f
atty acyl CoA, when measured under a fixed molar ratio of acyl CoA/alb
umin, was 16:1n-7>18:1n-9>18:2n-6>16:0>22:6n-3, and was thus not affec
ted by the fat composition of the diet. However, in all for but one ca
se, the SO and MO diets elicited a higher v(max) each substrate than e
ither the LF diet or the high fat OO diet. The apparent K-0.5 for the
different acyl CoA esters was generally lowest in LF-fed animals, and
highest in those fed the high-fat SO diet. Moreover, when compared wit
h the situation of animals fed high-fat diets, the K-0.5 Values of CPT
I in LF-fed animals for palmitoyl CoA and oleoyl CoA were low. This p
ossession by CPT I of a high ''affinity'' toward these nonessential fa
tty acyl CoAs, but a lower ''affinity'' toward linoleoyl CoA, the este
r of an essential fatty acid, may enable this latter fatty acid to be
spared from oxidation when its concentration in the diet is low. The d
ata also emphasize that palmitoleoyl CoA, if available in the diet, is
likely to be utilized by CPT I at a high rate.