Open AccessAttempts at Purifying the Galactose Carrier from Galactose‐Induced Baker's Yeast
Author(s) -
Haškovec C.,
Kotyk A.
Publication year - 1969
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1969.tb00614.x
Subject(s) - galactose , galactokinase , yeast , membrane , centrifugation , biochemistry , chemistry , chromatography , solubilization , labelling , sugar , escherichia coli , gene
1 An attempt was made to isolate the protein associated with the formation of the inducible d ‐galactose‐transporting system in baker's yeast. Of the several fractions obtained by centrifugation of homogenized yeast cells at different speeds only the fraction sedimenting at 40000 x g and containing a predominance of membranes was found to bind d ‐galactose, the dissociation constant being 0.2–0.6 mM. No galactokinase activity was found in this fraction. 2 The membrane proteins were solubilized using various technique but the amount of sugar bound by the solubilized proteins was lower than that bound by the intact membranes, the most promising appearing to be treatment with 1 M NaI. 3 Membrane proteins labelled by a double‐labelling technique were solubilized with 1 M NaI and separated on DEAE‐cellulose in a linear gradient of NH 4 HCO 3 . A peak of unequal labelling with 14 C and 3 H was identified both in normal baker's yeast and in a galactokinase‐less mutant and assumed to represent the inducible galactose carrier or a part of its transport system.