Trypsin-SBTI interaction in reverse micelles. A slow intermicellar exchange-dependent binding.

Area of Science:

• Supramolecular Chemistry
• Biophysical Chemistry
• Chemical Kinetics

Background:

• Solubilisate exchange in reverse micelles is crucial for reactions within the micellar core.
• Previous studies show rapid exchange for small molecules and macromolecules, faster than enzymatic turnover.

Purpose of the Study:

• To investigate the exchange dynamics between two macromolecules (trypsin and soybean trypsin inhibitor) within reverse micelles.
• To determine the rate-limiting steps and influencing factors in macromolecule-mediated reverse micelle exchange.

Main Methods:

• Utilized reverse micelle systems with varying sizes (controlled by water-to-surfactant ratio, ω₀).
• Studied the interaction and exchange kinetics between trypsin and soybean trypsin inhibitor.
• Analyzed the effect of temperature on the exchange and fusion processes.

Main Results:

• Macromolecule exchange between reverse micelles is dramatically slower (10³ times) compared to small molecule exchange.
• The fusion step, a key part of the exchange, is significantly hindered (10⁶ times slower).
• Reverse micellar size (ω₀) and temperature were identified as critical factors influencing fusion rates.

Conclusions:

• The exchange of macromolecules in reverse micelles is a much slower process than previously observed for smaller molecules.
• Micellar fusion is the rate-limiting step, with its rate dependent on micellar size and temperature.
• Macromolecules may play an active role in modulating the exchange process within reverse micelles.