The Key to Effective Catalytic Action is Pre-catalytic Site Activity Preceding Enzyme-substrate Complex Formation

Aims: i) To show that attractive electrostatic interaction is essential to stable enzyme-substrate formation, ii) to determine the minimum interparticle distance for maximum attractive interaction, iii) to determine the duration and the velocity of transit before enzyme substrate collision, and iv) to determine and show that the translational diffusion coefficient as time tends to infinity is much lower than at the beginning outside the influence of electrostatic interaction.

Study Design: Theoretical and Experimental.

Place and Duration of Study: Department of Chemistry and Biochemistry, Research Division, Ude International Concepts LTD (862217), B. B. Agbor, Delta State, Nigeria; Owa Alizomor Secondary School, Owa Alizomor, Ika North East, Delta State, Nigeria. The research lasted between June, 2016 and March, 2017.

Methodology: Bernfeld method of enzyme assay was used. Assays were carried out on Aspergillus oryzea salivary alpha amylase. Data obtained for the velocity of hydrolysis of starch were used to determine concentration of enzyme involved in catalytic activity. The concentrations of the enzyme and substrate were used to calculate the maximum interparticle distance between the enzyme and substrate in a reaction mixture volume equal to 2 mL.

Results: The terminal diffusion coefficient was either 3.982±0.417 exp (-15) m2 /s (Mean±SD) or 3.933±0.427 exp (-15) m2 /s (Median±SD). The duration of transit through the shortest interparticle distance and the velocity were either 3.560±0.373 ms (Mean±SD) or 3.577±0.361 ms (Median±SD) and either 2.436±0.163 mm/s (Mean±SD) or 2.487±0.169 mm/s (Median±SD) respectively.

Conclusion: The electrostatic interaction model is suitable for the description of the binding of the enzyme to the substrate. The diffusion coefficient was expectedly « bulk diffusion coefficient. The work done (a function of hydrodynamic radius) by the advancing enzyme per unit time is unique to the nature of the bullet molecule. Diffusion coupled with attractive electrostatic interaction between combining particles could enhance the frequency of effective collision of the particles.