Fructosylation of human insulin causes AGEs formation, structural perturbations and morphological changes: an in silico and multispectroscopic study

Abstract

Fructosylation of proteins results in the formation of advanced glycation end-products (AGEs). A diet rich in fructose along with hyperglycemia can cause fructose mediated glycation (fructosylation) of proteins, which results in AGEs formation. Insulin is a peptide hormone that is glycated when exposed to carbohydrates such as glucose. In this study, we have analysed the interaction of insulin with fructose and biophysically characterized fructose modified insulin. In silico studies performed through molecular docking and molecular dynamics simulation revealed that fructose binds to insulin with strong affinity resulting in the formation of insulin-fructose complex. Fructosylation of insulin caused hyperchromicity, loss of intrinsic fluorescence, gain in AGEs specific fluorescence and elevated the carbonyl and fructosamine content. Enhanced thioflavin T fluorescence suggested the presence of fibrillar structures at higher concentrations of fructose. Electron microscopy revealed the formation of characteristic amorphous and amyloid like aggregates at lower and higher concentrations of fructose, respectively. These findings show that fructosylation of insulin causes AGEs production, aggregation and alters its gross structural integrity. These changes may reduce the biological activity of insulin that can aggravate conditions like type II diabetes mellitus.

Communicated by Ramaswamy H. Sarma

Keywords:

• Human insulin
• fructose
• fructosylation
• AGEs
• amyloid aggregates

Acknowledgments

Authors are thankful to Department of Biochemistry, J.N. Medical College for providing research facilities and University Sophisticated Instrumentation (USIF), Aligarh Muslim University, for electron microscopy.

Disclosure statement

The authors declare no conflict of interest.

Credit author statement

Asif Ali: Conceptualization, validation and supervision.

Ali Raza: Methodology, investigation, validation, data curation and writing.

Riaz Mahmood: Supervision, validation, reviewing and editing.

Safia Habib: Reviewing, editing.

Mohd Talha: Methodology, investigation, and validation.

Shifa Khan: Reviewing and editing.

Md Amiruddin Hashmi: Methodology, software and editing.

Taj Mohammad: Methodology and software.

Additional information

Funding

Ali Raza is thankful to the University Grants Commission, New Delhi for providing Maulana Azad Fellowship vide grant number No. F. 82-27/2019 (SA-III).