Abstract
Bovine seminal RNase (BS-RNase) is a homodimeric enzyme with a cytotoxic activity selective for tumor cells. In this study, the relationships of its cytotoxic activity to its dimeric structure and its resistance to the cytosolic RNase inhibitor (cRI) are investigated systematically by site-directed mutagenesis. The results show that (1) the dimericity of BS-RNase is essential for its full cytotoxic action; (2) the role of the dimeric structure in the antitumor activity is that of making the enzyme insensitive to the cytosolic RNase inhibitor; (3) a RNase may not be completely insensitive to cRI to exploit a full cytotoxic potential.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3 Cells
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Amino Acid Substitution / genetics
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Animals
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Antineoplastic Agents / antagonists & inhibitors*
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Antineoplastic Agents / chemistry*
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Antineoplastic Agents / metabolism
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Antineoplastic Agents / toxicity
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Arginine / genetics
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Cattle
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Cytosol / enzymology*
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Dimerization
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Disulfides / chemistry
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Drug Resistance
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Endoribonucleases / antagonists & inhibitors*
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Endoribonucleases / chemistry*
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Endoribonucleases / genetics
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Endoribonucleases / toxicity
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Enzyme Inhibitors / pharmacology*
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Glutamic Acid / genetics
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Growth Inhibitors / antagonists & inhibitors
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Growth Inhibitors / chemistry
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Growth Inhibitors / genetics
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Growth Inhibitors / toxicity
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Lysine / genetics
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Mice
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Mutagenesis, Site-Directed
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Proteins / pharmacology*
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Recombinant Proteins / antagonists & inhibitors
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Recombinant Proteins / chemistry
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Recombinant Proteins / toxicity
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Semen / enzymology*
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Serine / genetics
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Tryptophan / genetics
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Tumor Cells, Cultured
Substances
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Antineoplastic Agents
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Disulfides
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Enzyme Inhibitors
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Growth Inhibitors
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Proteins
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Recombinant Proteins
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Glutamic Acid
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Serine
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Tryptophan
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Arginine
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Endoribonucleases
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ribonuclease SPL
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Lysine