[Experiments on the modification of the distribution of the activity of various alpha-L-arabinofuranosidases following i.v. application in tumor-bearing mice].

Graffi et al. have proposed the use of exogenous enzymes for selective cleavage of inactive transport forms of cancerostatic substances in tumor tissue. Enzymes appropriate for this purpose should, if possible, show also a certain enrichment in the tumor tissue. In studies on the pH-labile alpha-L-arabinofuranosidase from G. myabena in tumor-bearing mice, under defined conditions in the tumors there could be demonstrated a higher concentration of the active form of the enzyme than in most of the normal tissues. However, the enzyme activity is eliminated from the organism in a relatively short time through excretion and inactivation. The application of glucose led to a strong increase of activity of the enzyme injected, both in the tumors and in the normal tissues. It has been shown in the present investigations that this increase in the enzyme activity can be curtailed more strongly in normal tissue by alkali application than in the tumors. In this way, a distribution of the enzyme activity favorable for therapy experiments is obtained. Only in the kidney and urine has a higher activity of the applied enzyme been measured than in the tumors. In the second part of this work it has been attempted to achieve accumulation of activity of the pH-stable alpha-L-arabinofuranosidase from A. niger through application of angiotensin, but no positive results have been reached under the various experimental conditions used.