Enolases from fluoride-sensitive and fluoride-resistant streptococci

Area of Science:

• Microbiology
• Biochemistry
• Enzyme kinetics

Background:

• Fluoride sensitivity varies among Streptococcus strains.
• Enolase is a key enzyme in glycolysis, a metabolic pathway.
• Understanding enzyme inhibition by fluoride is crucial for microbial studies.

Purpose of the Study:

• To investigate the kinetic properties of enolase from different Streptococcus strains with varying fluoride sensitivities.
• To determine if differences in enolase enzyme kinetics explain variations in glycolytic fluoride sensitivity.

Main Methods:

• Purification of enolase enzymes from Streptococcus salivarius (fluoride-sensitive and resistant strains), Streptococcus sanguis, and Streptococcus mutans.
• Enzyme kinetic analysis, including determination of Michaelis constants, pH and Mg2+ optima.
• Fluoride inhibition studies, assessing competitive inhibition and calculating inhibition indices.
• Standardized conditions for percent inhibition measurements.

Main Results:

• Purified enolases from all tested strains exhibited high similarity in kinetic properties (Michaelis constants, pH and Mg2+ optima).
• Fluoride inhibition was competitive, required inorganic phosphate, and showed similar inhibition indices across strains.
• Percent inhibition by fluoride was comparable among the purified enzymes under standardized conditions.
• Inhibition was significantly reduced at pH 6.0.

Conclusions:

• The kinetic properties of enolase enzymes are highly conserved across Streptococcus strains with different fluoride sensitivities.
• Observed differences in glycolytic fluoride sensitivity among Streptococcus strains are not attributable to kinetic variations in their respective enolase enzymes.