FTIR study of secondary structure changes in Epidermal Growth Factor by gold nanoparticle conjugation

• Published in: Biochimica et biophysica acta Vol. 1862; no. 3; pp. 495 - 500
• Main Authors: Bhattacharjee, T.T., Castilho, M.L., de Oliveira, I.R., Jesus, V.P.S., Hewitt, K.C., Raniero, L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2018
• Subjects: adverse effects; Bifunctional nanoprobe synthesis; crystal structure; epidermal growth factor; Epidermal Growth Factor (EGF); Fourier transform infrared spectroscopy; FTIR; Gold nanoparticle; lipoic acid; manufacturing; nanogold; nanoparticles; neoplasms; photochemotherapy; Secondary structure; Targeted Photodynamic therapy; Bifunctional nanoprobe synthesis; Secondary structure; Targeted Photodynamic therapy; Epidermal Growth Factor (EGF); FTIR; Gold nanoparticle
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2017.11.009

Conformation of protein is vital to its function, but may get affected when processing to manufacture products. It is therefore important to understand structural changes during each step of production. In this study, we investigate secondary structure changes in the targeting protein Epidermal Growth Factor (EGF) during synthesis of theranostic bifunctional nanoparticle, devised for Photodynamic therapy of breast cancer. We acquired FTIR spectra of EGF; unconjugated, post treatment with α-lipoic acid, attached to gold nanoparticle, and bound to the bifunctional nanoprobe. We observed decreasing disordered structures and turns, and increasing loops, as the synthesis process progressed. There was an overall increase in β-sheets in final product compared to pure EGF, but this increase was not linear and fluctuated. Previous crystal structure studies on EGF-EGFR complex have shown loops and β-sheets to be important in the binding interaction. Since our study found increase in these structures in the final product, no adverse effect on binding function of EGF was expected. This was confirmed by functional assays. Such studies may help modify synthesis procedures, and thus secondary structures of proteins, enabling increased functionality and optimum results. [Display omitted] •Epidermal Growth Factor (EGF) secondary structure vital for function•EGF processing for targeted Photodynamic therapy may affect secondary structure.•Our FTIR studies show increase in β-sheets and loops in EGF during processing.•Previous reports suggest these structures important for EGF binding to its receptor.•Study thus shows possibility of improved function in final product.