Abstract
Among five ribosome-inactivating proteins tested only saporin-S6 could efficiently release the adenine from adenosine 20 of the synthetic oligoribonucleotide (SRD RNA) mimic of the sarcin/ricin domain of rat 28S rRNA with a Km of 9 microM and a kcat of approximately 0.4 min(-1) at pH 7.6. The optimal pH for the depurination activity of saporin-S6 is 5.0. However, saporin-S6 lost its site-specificity of depurination on SRD RNA around the optimal pH. The non-specific depurination activity of saporin-S6 was dependent on the enzyme concentration and pH conditions. These results are valuable to understand the diversity and the depurination mechanism of ribosome-inactivating proteins.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenine / metabolism*
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Animals
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Binding Sites
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Deoxyribonucleases / chemistry
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Deoxyribonucleases / metabolism
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Dose-Response Relationship, Drug
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Electrophoresis, Agar Gel
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Hydrogen-Ion Concentration
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Immunotoxins*
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Kinetics
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Molecular Mimicry
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N-Glycosyl Hydrolases*
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Oligoribonucleotides / chemistry
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Oligoribonucleotides / metabolism
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Plant Proteins / chemistry
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Plant Proteins / metabolism*
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RNA, Ribosomal, 28S / chemistry
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Rats
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Ribosome Inactivating Proteins, Type 1
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Saporins
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Substrate Specificity
Substances
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Immunotoxins
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Oligoribonucleotides
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Plant Proteins
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RNA, Ribosomal, 28S
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Ribosome Inactivating Proteins, Type 1
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Deoxyribonucleases
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N-Glycosyl Hydrolases
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Saporins
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Adenine