Naghmeh Sattarahmady, Ali A. Moosavi-Movahedi,
Volume 7, Issue 1 (7-2007)
Abstract
The interaction of reducing carbohydrates with proteins leads to a cascade of reactions that are known as glycation or Maillard reaction that have important roles in diabetic complications. In this minireview, structural changes of glycated human serum albumin (GHSA) via various sugars in different incubation times, which reported in scientific literature as well as our research, were reported. Our studies showed glycation induced structural changes for Human Serum Albumin (HSA). In glycation process of HSA after 21 days incubation, glucose separates from HSA and induced the formation of molten globule state that is relative to several diseases that originate from molten globule state in proteins. Also, glycation of HSA induced aggregation states and amyloid formation as well as decreased surface tension which plays a role of denaturant for protein as a surfactant. In following, we showed that alginate as a sugar polymer decreased glycation reaction in HSA. Finally, it is compared the structural changes of artificial and in vitro interaction of sugars with HSA as well as diabetic patients HSA. The results show the number of arginine residues in HSA of diabetic patients is more modified relative to lab samples.
Maryam Chinisaz, Azadeh Ebrahim-Habibi, Parichehreh Yaghmaei, Kazem Parivar, Ahmad- Reza Dehpour,
Volume 13, Issue 4 (5-2014)
Abstract
Background: The flexible structure of proteins is one important factor in the formation of ordered aggregates (amyloid fibril). This is a major problem for therapeutic proteins such as insulin. Study on the induction and inhibition of insulin fibrillation process with specific compounds such as aromatic derivatives may provide useful information about means of stabilization of protein structures.
Methods: To induce fibrillation, regular insulin was incubated in phosphate buffer (pH=7.4) during 24 hours. Amyloid formation was investigated by using Congo red absorbance and transmission electron microscopy (TEM). Then nodular amyloidosis was observed in mice upon amyloid fibril injection, after which the excised nodule was studied by Congo red staining and polarized light microscopy. Then, some aromatic compounds effect was investigated on the fibrillation process.
Results: Regular insulin form mature amyloid fibrils at pH=7.4, 37°C after 24 hours. Silibinin had the highest inhibitory effect on that process. Furthermore, Amyloid fibril injection in mice caused nodular amyloidosis.
Conclusion: Regular insulin has a high potential to undergo amyloid aggregation. Nodular amyloidosis confirms fibril formation by insulin under in vitro condition. Silibinin could be considered as a potential compound capable to increase protein structure stability.
