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Masahiko Suzuki, L-Leucine Transport in Isolated Protoplasts of Vinca Suspension Culture: Characterization of Uptake, Plant and Cell Physiology, Volume 22, Issue 7, November 1981, Pages 1269–1278, https://doi.org/10.1093/oxfordjournals.pcp.a076279
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Abstract
The uptake of L-leucine into Vinca protoplasts was studied under various conditions. The uptake was highly pH-dependent, with the optimal pH between 3.0 and 4.0. The uptake was also energy dependent, since azide, 2,4-dinitrophenol (DNP), carbonyl cyanide m-chlorophenyl hydrazone (CCCP), and iodoacetate inhibited the uptake. Oligomycin, N,N′-dicycIohexyI carbodiimide (DCCD) and vanadate, but not ouabain, inhibited the uptake, suggesting that ATPase for H+ electrogenic extrusion was necessary to the uptake of L-leucine. The uptake showed stereospecificity, but was partially inhibited by other L-amino acids. A kinetic study of the uptake showed that the uptake was multiphasic with three saturable phases and one unsaturable phase which occurred at concentrations of L-leucine over 1 mM. The Km values of the three affinity sites were 1.4 × 10−3M, 1.3 × 10−4M, 4.3 × 10−5M; the maximum velocity values were 3.3 × 10−8, 4.5 × 10−9, 1.8 × 10−9 mol/10 min/4 × 106 cells.
