We have identified three methyl esters that have a potent stimulatory effect on the cotransport system responsible for the absorption of most essential amino acids in the silkworm Bombyx mori. L-Leucine methyl ester, the most powerful activator, determined a large dose-dependent, K+-independent increase of leucine uptake into midgut brush border membrane vesicles. Kinetic experiments revealed non-essential mixed-type activation, with Ka values of 27±2 and 47±8 μM in the presence and in the absence of K+, respectively. The activation increased Km twofold, and Vmax up to 18-fold depending upon the experimental conditions. Leucine uptake mediated by the amino acid uniport appears to be unaffected by the activator.
Leucine methyl ester is a powerful allosteric activator of the neutral amino acid cotransport system in Bombyx mori larval midgut / P. Parenti, M.G. Leonardi, M. Forcella, M. Casartelli, A. Pugliese, G.M. Hanozet, B. Giordana. - In: INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY. - ISSN 0965-1748. - 32:7(2002), pp. 719-727.
Leucine methyl ester is a powerful allosteric activator of the neutral amino acid cotransport system in Bombyx mori larval midgut
M.G. Leonardi;M. Casartelli;B. Giordana
2002
Abstract
We have identified three methyl esters that have a potent stimulatory effect on the cotransport system responsible for the absorption of most essential amino acids in the silkworm Bombyx mori. L-Leucine methyl ester, the most powerful activator, determined a large dose-dependent, K+-independent increase of leucine uptake into midgut brush border membrane vesicles. Kinetic experiments revealed non-essential mixed-type activation, with Ka values of 27±2 and 47±8 μM in the presence and in the absence of K+, respectively. The activation increased Km twofold, and Vmax up to 18-fold depending upon the experimental conditions. Leucine uptake mediated by the amino acid uniport appears to be unaffected by the activator.Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.