Kinetic behaviour of a repressible acid phosphatase from the yeast Yarrowia lipolytica: a comparative study between the solubilized enzyme, the enzyme bound to cell-wall fragments and the enzyme bound to intact cells.
(1) The substrate specificities and types of inhibitors of a repressible acid phosphatase from the yeast Yarrowia lipolytica as solubilized enzyme, enzyme bound to cell-wall fragments and enzyme bound to the intact cell were found to be essentially the same. (2) A similar pattern for the activation of the enzymatic activity by ionic strength was found for solubilized enzyme, the enzyme in cell-wall fragments and the enzyme in intact cells. (3) v[S] studies with all three locations of the enzyme revealed non-linear Eadie-Hofstee plots with concave-up curves of the negative cooperativity type; these were correctly fitted with a rate equation of 2:2 degree polynomial quotient. In all cases, the same behaviour was obtained and no new kinetic properties were observed when the enzyme was bound to the cell-wall matrix with respect to the solubilized enzyme. (4) Inhibition by phosphate was characterized for the three locations of the enzyme by v[I] and v[S] studies. The same pattern of partial inhibition and non-Michaelian inhibition of 'non-competitive' nature was observed for all three forms. (5) The above results are interpreted in terms of the hypothesis that the cell wall of Y. lipolytica has a slight negative charge but behaves as a permeable matrix that does not lead to novel characteristics regarding the catalytic and regulatory properties shown by the enzyme molecule in free solution.
González
F J
FJ
Departamento de Química Física, Facultad de Farmacia, Universidad de Salamanca, Spain.
Fauste
C
C
Burguillo
F J
FJ
Dominguez
A
A
D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D007700:Kinetics; D008433:Mathematics; D010710:Phosphates / Q000494:pharmacology; D013379:Substrate Specificity; D015003:Yeasts / Q000201:enzymology*
D010710:Phosphates; D000135:Acid Phosphatase