Protoplasts of Schizosaccharomyces pombe: an improved method for their preparation and the study of their guanine uptake.

A new method is described for the efficient conversion of Schizosaccharomyces pombe cells into protoplasts. The following parameters of guanine uptake determined in whole cells were unchanged in protoplasts: Km value, requirement for an energy source, sensitivity to competitive inhibitors, pH optimum, as well as the typical variation of the initial velocity of uptake observed during the growth phase.