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Substrate specificity of monomeric and dimeric alpha-sarcin
1Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan.
FEBS Letters
|May 13, 1996
Summary
Monomeric alpha-sarcin inactivates ribosomes and hydrolyzes RNA, unlike its dimeric form. Both forms exhibit ribonuclease and deoxyribonuclease activity, with some inhibition reversible by protein renaturation.
Area of Science:
- Biochemistry
- Molecular Biology
Background:
- Alpha-sarcin is a fungal protein known for its enzymatic activity.
- The quaternary structure (monomeric vs. dimeric) of alpha-sarcin may influence its substrate interactions.
Purpose of the Study:
- To investigate the substrate specificity of monomeric and dimeric forms of alpha-sarcin.
- To compare the ribonuclease and deoxyribonuclease activities of the two alpha-sarcin forms.
Main Methods:
- Membrane blotting procedures.
- In situ RNA-impregnated gel electrophoresis.
- Analysis of activity on ribosomes, mini-stem-loop RNA, and supercoiled DNA.
Main Results:
- Monomeric alpha-sarcin inactivates ribosomes and hydrolyzes mini-stem-loop RNA, while dimeric alpha-sarcin does not.
- Both forms are effective ribonucleases with identical purine base specificity.
- Alpha-sarcin acts as a deoxyribonuclease on supercoiled DNA.
- Sodium dodecyl sulfate (SDS) inhibits both ribonuclease and deoxyribonuclease activity, with ribonuclease inhibition being reversible upon protein renaturation.
Conclusions:
- The monomeric form of alpha-sarcin is essential for its ribosome-inactivating and RNA hydrolyzing functions.
- Both monomeric and dimeric alpha-sarcin possess nuclease activities, but their substrate specificities differ.
- Enzyme structure and environmental factors like SDS significantly impact alpha-sarcin's enzymatic functions.