SOME CHARACTERISTICS OF STREPTOCOCCAL NICOTINAMIDE ADENINE DINUCLEOTIDASE AND STREPTOLYSIN O

Area of Science:

• Microbiology
• Biochemistry
• Enzymology

Background:

• Streptococcus pyogenes produces extracellular enzymes like nicotinamide adenine dinucleotidase (NADase) and streptolysin O.
• Understanding the biochemical properties of these enzymes is crucial for studying bacterial pathogenesis.

Purpose of the Study:

• To isolate and characterize nicotinamide adenine dinucleotidase (NADase) from Streptococcus pyogenes.
• To determine the molecular weight and amino acid composition of NADase.
• To investigate the stability and purity of the isolated NADase.

Main Methods:

• Isolation of NADase using diethylaminoethyl-cellulose chromatography.
• Enzyme characterization through ultracentrifugation and paper chromatography after dinitrofluorobenzene (DNFB) treatment.
• Molecular weight estimation using Visking dialysis casing with known molecular weight standards.
• Amino acid analysis of NADase preparations.

Main Results:

• NADase was successfully isolated free from streptolysin O and contained a trace of deoxyribonuclease.
• Ultracentrifugation showed no moving boundary, and DNFB treatment yielded a single yellow spot on chromatograms.
• Dialysis experiments indicated a molecular weight between 2,500 and 3,000 for NADase.
• Amino acid analysis revealed high proline and glycine content and low sulfur-containing amino acids, suggesting arginine as a possible N-terminal amino acid.

Conclusions:

• Streptococcal NADase is a distinct enzyme with a molecular weight likely between 2,500 and 20,000.
• The enzyme possesses a unique amino acid profile.
• Streptolysin O exhibits irreversible instability and low sulfur-containing amino acid content.