Reversible association of proteins into sub-visible amorphous aggregates using short solubility controlling peptide tags

Publication date: Available online 22 September 2017 Source:Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics Author(s): Md. Golam Kabir, Mohammad Monirul Islam, Yutaka Kuroda Careful analysis of sub-visible amorphous aggregates, where proteins associate non- covalently in either native or denatured states without forming a specific quaternary structure, may shed insight into the mechanisms of protein aggregation and solubility. Here we report a biophysical and biochemical analysis of our model protein, a bovine pancreatic trypsin inhibitor variant (BPTI-19A), whose oligomerization were controlled by attaching solubility controlling peptide tags (SCP tags) to its C terminus, which are short peptides composed of a single type of amino acid that modulate protein solubility. The dynamic light scattering and static light scattering at 25°C indicated that 11 out of 15 SCP tags merely affected the hydrodynamic radius and light scattering intensity of our reference variants BPTI-19A and BPTI-C2G. On the other hand, hydrophobic SCP tags composed of 5 Ile (C5I) or 5 Leu (C5L) were associated into sub-visible aggregates. Circular dichroism indicated that all tagged BPTI variants had the same secondary structure contents as the reference BPTI-19A at 25°C, suggesting that BPTI-C5I and C5L kept their native structure upon association. Furthermore, the thermal denaturation of all of the BPTI variants were fully reversible and typical of natively folded small globular pro...

Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - September 23, 2017 Category: Biochemistry Source Type: research