Intracellular protease profile during differentiation of Physarum flavicomum haploid cells



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Distinct intracellular protease profiles were demonstrated during encystment of Phys arum flavicomum when cell extracts were subjected to isoelectric focusing employing an ampholyte range of pH 3.5 to 10. Paralleling microcyst formation was a substantial decrease in intracellular protein content. An increase in proteolytic activity was observed that accounts for the intracellular protein degradation during differentiation . Crude extracts of myxamoebae, 12 hour, and 96 hour microcysts were electrofocused. The column eluates exhibited Azocoll hydrolyzing activity over a wide pH range. Acidic leucine aminopeptidases were detected during the entire encystment process. Higher proteolytic activity was detected in cyst extracts after isoelectric focusing than before. This may demonstrate the presence of an inhibitor (repressor) in dormant cells accounting for the lowered proteolytic activity of the cells. Activation or synthesis of specific proteolytic enzymes during conditions of nutrient imbalance could provide the necessary materials (amino acids) for differentiation to proceed.