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Effects of inhibitor, competitors and temperature on transport of carbohydrate in Crithidia luciliae
Author(s) -
Min Hong S.
Publication year - 1966
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040680304
Subject(s) - sorbose , carbohydrate , monosaccharide , concentration gradient , chemistry , diffusion , biophysics , biochemistry , chromatography , biology , fructose , thermodynamics , physics
Abstract Effects of KCN (10 −4 M), simultaneous presence of varying concentrations of D‐glucose and L‐sorbose, and temperature on transport of carbohydrate in C. luciliae have been studied. The rate of carbohydrate entrance is inhibited, in all sugars used, ranging from 19% to 70% inhibition at 0.5 mM external concentrations. However, this inhibitor does not affect transport from external concentrations of the order of 0.02 M. At 20 mM external concentration, the rate of L‐sorbose entrance is greatly inhibited by the simultaneous presence of D‐glucose, and the transport mechanism shows enormously greater affinity for glucose than for other monosaccharides. However, at 0.5 mM external concentration, the rate of sorbose entrance is not inhibited at all by the simultaneous presence of D‐glucose. In the temperature interval 15°–25°C, the Q 10 for rate of entrance when the external concentration is 0.5 mM is 2.8 times larger than the Q 10 when the external concentration is 20 mM. These data are interpreted as strongly suggesting two mechanisms for carbohydrate entrance: (a) facilitated diffusion, of importance only at high external concentrations; (b) an active transport mechanism, active at low external concentrations and dependent upon a supply of metabolic energy. These results are compared with those reported in the literature for other types of cells.