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Nejvíce citované: 4947178

7 citací v PubMed Filtry

Nejvíce citovaný článek - PubMed ID 4947178

Uptake of amino acids by actidione-treated yeast cells. II. Effect of incubation conditions and metabolic inhibitors

Folia microbiologica. 1971 ; 16 (6) : 445-50.

Folia Microbiol (Praha)
ISSN 0015-5632
Zdroj

Článek

Uptake of L-lysine by a double mutant of Saccharomyces cerevisiae

Folia microbiologica. 1988 ; 33 (4) : 285-91.

Folia Microbiol (Praha)
ISSN 0015-5632
Zdroj

A gap1 can1 mutant of Saccharomyces cerevisiae with a single lysine transport system remaining was used to study detailed kinetics of this transport. Its half-saturation constant was 78 mumol per litre, its maximum rate of transport was 0.29 mumol L-lysine per g dry matter per minute, both parameters being lower by more than an order of magnitude in comparison with the GAP system. The pH optimum lay at very acid values of about 3, the temperature dependence without any transition point showed an activation energy of 48 kJ/mol. The transport was inhibited by common metabolic inhibitors (3'-chlorophenylhydrazonomalononitrile, antimycin, 2-deoxy-D-glucose, sodium arsenate) as well as by a membrane-active one (uranyl nitrate). The specificity of the system was extremely high, none of the natural amino acids acting as competitor to L-lysine. The maximum accumulation ratio attained (at about 5 mg dry matter per mL) was 100: 1-120: 1, in agreement with the measured protonmotive force under the assumption of 1 H+ ion being transported with 1 lysine molecule. The ratio decreased with increasing external concentration of lysine to as little as 4: 1 at 1 mmol lysine per litre. It also decreased with increasing suspension density and it was at extremely low suspension densities (0.2 mg dry matter per mL) that ratios of as much as 500: 1 were reached. Application of group-specific inhibitors showed that the active site of the carrier contains an essential histidine residue.

MeSH
glukosa metabolismus MeSH
koncentrace vodíkových iontů MeSH
lysin farmakokinetika farmakologie MeSH
Saccharomyces cerevisiae účinky léků genetika metabolismus MeSH
spotřeba kyslíku účinky léků MeSH
teplota MeSH
Publikační typ
časopisecké články MeSH
Názvy látek
glukosa MeSH
lysin MeSH

Článek

Stimulation of amino acid transport in Saccharomyces cerevisiae by metabolic inhibitors

Folia microbiologica. 1978 ; 23 (4) : 286-91.

Folia Microbiol (Praha)
ISSN 0015-5632
Zdroj

Inhibitors of energy metabolism (3-chlorophenylhydrazonomalononitrile, antimycin A, iodoacetamide, dicyclohexylcarbodiimide) but not of transport (uranyl ions) stimulate at low concentrations the uptake of L-leucine, L-glutamic acid, L-arginine and, to a lesser degree, of 2-aminoisobutyric acid in Saccharomyces cerevisiae. The effect is apparent only after augmenting the energy reserves of cells by preincubation with D-glucose or, more strikingly, with ethanol. It is absent in a mutant (op1) lacking the translocation system for ADP--ATP in mitochondria. The presence of two different energy reserves for amino acid transport is indicated (one in energy-poor, the other in energy-rich cells). The stimulating effect appears to be caused by a retarded degradation of the transport proteins as occurs at a lowered level of mitochondria-produced ATP.