Stability of horse muscle acylphosphatase to heat and to urea.

The research article explores the thermal stability of horse muscle acylphosphatase in different environments. It suggests that the enzyme is stable in acidic environments, but can be inactivated in alkaline conditions, unless the concentration or ionic strength is increased. The effect of high urea concentrations and its instantaneous reversal of enzyme’s activity is also explored.

Investigation of thermal stability

The scientists studied the thermal stability of horse muscle acylphosphatase, an enzyme, in different environments:

• The enzyme’s inactivation constants were measured at different pH and temperature values.
• The differential spectra technique was used for further investigation.

Acidic versus Alkaline environment

The enzymes showed varying stability based on the pH of their surroundings:

• In an acidic environment, the enzyme demonstrated high thermal stability.
• However, in an alkaline medium, the enzyme became inactive.

Protection against inactivation

Two methods were found that could protect the enzyme against inactivation in an alkaline environment:

• Increasing the concentration of the enzyme was found to provide some protection.
• Raising the ionic strength of the solution also protected against inactivation.

Effect of Urea

The enzyme’s stability and activity under high urea concentrations was also studied:

• Spectral changes at 230 nm indicated a link with urea inactivation.
• Remarkably, enzymatic activity could be instantly and almost completely restored by diluting the urea.