Proteinases of Leishmania mexicana amastigotes and promastigotes: analysis by gel electrophoresis.

The proteinases of Leishmania mexicana mexicana amastigotes and promastigotes have been analysed by electrophoresis on polyacrylamide gels containing denatured haemoglobin. Eleven bands of activity were detected indicating multiple proteinases. These were significant quantitative and qualitative differences between the proteinases of the two developmental forms. Four, B-E, were present in both forms but were of much higher activity in the amastigote. There were two major activities in promastigotes, A and D. The other proteinases, F-K, were of lower activity; I and K were not detected in promastigotes. All proteinases were active optimally at pH 4.0. Most of them, including the major proteinases A-E, were thiol proteinases since they were stimulated by 1 mM dithiothreitol and were sensitive to inhibitors such as HgCl2, leupeptin, antipain and iodoacetic acid.