Study of bovine hemoglobin dissociation by multiangle laser light-scattering method

Area of Science:

• Biochemistry
• Protein Chemistry
• Biophysical Chemistry

Background:

• Hemoglobin (Hb) is an oligomeric protein composed of four subunits.
• Hb can dissociate from a tetramer into dimers, a process termed hemoglobin dissociation.
• Understanding Hb dissociation is crucial for its function and stability.

Purpose of the Study:

• To investigate the dissociation of bovine hemoglobin (Hb).
• To determine the effect of concentration on bovine Hb molecular weight.
• To assess the influence of pH on bovine Hb stability.

Main Methods:

• Multiangle laser light-scattering (MALS) was employed to measure average molecular weights.
• Microbatch MALS and on-line size-exclusion chromatography with MALS and refractive index detection were utilized.
• Bovine Hb solutions at varying concentrations and pH were analyzed.

Main Results:

• Bovine Hb exhibited an average molecular weight of approximately 54 kDa at concentrations >1.5 mg/mL.
• At concentrations <0.03 mg/mL, the average molecular weight decreased to about 36 kDa, indicating dissociation.
• The tetramer form of bovine Hb demonstrated greater stability within the pH range of 6-9.

Conclusions:

• Bovine Hb concentration significantly influences its quaternary structure, with dissociation occurring at lower concentrations.
• pH plays a critical role in the stability of bovine Hb, with optimal stability observed in neutral to slightly alkaline conditions.
• The study provides quantitative insights into bovine Hb dissociation dynamics and stability parameters.