Determination of Molar Mass and Its Relationship with Free Energy of Activation: A Case Study on Human Salivary Alpha Amylase

Aims: The objectives of the research were (i) to show that the mass concentration, molar mass of one-active site enzyme, and consequently, the type of human salivary alpha amylase (HSαA), can be determined using kinetic parameter dependent model, (ii) to show that the free energy of activation for hydrolysis of substrate is usually related to molar mass.

Study Design: Experimental.

Place and Duration of Study: Department of Biochemistry, Ambrose Alli University and Research Division of Ude International Concepts Limited (RC 862217) B. B. Agbor Delta, Nigeria. The research spanned between June, 2008 and August, 2016.

Methodology: Bernfeld method of enzyme assay was used. Assays were carried out on diluted commercial human salivary alpha amylase (HSαA) and crude extract of HSαA.

Results: Mean values of calculated mass concentration and molar mass of the enzyme were 171.09±0.64 mg/l and 61.92±0.64 kDa respectively (from 20 calculations). The concentration of crude extract of HSαA was 94.5±0.4 mg/l. With the old model the free energy of activation (△Ga) value is 51.19±0.12 kJ/mol (n = 20). Using directly the new model the value is 51.21±0.08 kJ/mol.

Conclusion: It is concluded that the model can be used to accurately determine the concentration of the enzyme and its △Ga using either standard solution or crude extract. Therefore, as a corollary, the molar mass of such enzyme can be determined given well defined concentration of the enzyme. The enzyme purchased from Sigma – Aldrich, USA, may be the glycosylated HSαA.