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Ribonucleases from porcine brain. Partial purification and properties.
Journal of Biochemistry
|October 1, 1976
Summary
This study partially purified two porcine brain ribonucleases: an acidic exonuclease and an alkaline pyrimidine-specific endoribonuclease. Both enzymes degraded yeast RNA but not DNA, with differing stabilities.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Ribonucleases (RNases) play crucial roles in RNA metabolism and degradation.
- Understanding the properties of different RNases is essential for molecular biology applications.
- Porcine brain is a potential source of various enzymatic activities.
Purpose of the Study:
- To partially purify and characterize acid and alkaline ribonucleases from porcine brain.
- To determine the substrate specificity, optimal pH, molecular weight, and stability of these enzymes.
Main Methods:
- Partial purification of acid and alkaline ribonucleases from porcine brain acetone powder.
- Enzyme activity assays using yeast RNA and heat-denatured calf thymus DNA.
- Determination of optimal pH, molecular weight, and stability (heat and acid).
Main Results:
- An acidic ribonuclease (approx. 70,000 Da) acting as an exonuclease was purified, with optimal activity at pH 5.9.
- An alkaline ribonuclease (25,000-26,000 Da), a pyrimidine-specific endoribonuclease, was purified, with optimal activity at pH 7.4.
- Neither enzyme hydrolyzed DNA or bis(rho-nitrophenyl) phosphate; the acid enzyme was heat and acid labile, while the alkaline enzyme was relatively stable.
Conclusions:
- Porcine brain contains distinct acid (exonuclease) and alkaline (endoribonuclease) ribonuclease activities.
- These enzymes exhibit different biochemical properties, including substrate specificity and stability.
- The findings contribute to the understanding of RNA-degrading enzymes in mammalian brain tissue.