Deoxyribonuclease from Salmon Testes : I. Purification and properties

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Deoxyribonuclease II (DNase II) is an enzyme with significant biological roles.
• Efficient purification methods are crucial for studying enzyme kinetics and function.
• Salmon testis is a potential source for DNase II isolation.

Purpose of the Study:

• To develop and describe a purification procedure for salmon testis deoxyribonuclease II.
• To characterize the enzyme's activity, stability, and substrate specificity.
• To separate DNase II from other enzymatic activities present in the crude extract.

Main Methods:

• Acid extraction of salmon testis tissue.
• Fractional precipitation using ammonium sulfate.
• Heat denaturation to remove contaminating proteins.
• Ethanol fractionation for enzyme isolation.

Main Results:

• A purification process yielding over 50% activity retention and 20,000-fold enrichment was established.
• The purified enzyme demonstrated specific deoxyribonuclease II activity, separating it from RNase, phosphatase, phosphodiesterase, and protease.
• DNase II degraded native DNA more rapidly than heat-denatured DNA and did not hydrolyze apurinic acid.

Conclusions:

• The described multi-step procedure effectively purifies salmon testis DNase II.
• The enzyme exhibits distinct substrate preferences and is most stable within a specific pH range (4-5).
• Optimal enzyme activity is dependent on electrolyte concentration and specific pH (4.8) and temperature (55°C) conditions.