Guanidine hydrochloride denaturation of glycosylated and deglycosylated stem bromelain.
Glycosylation is one of the major naturally occurring covalent modifications of proteins. We have used stem bromelain, a thiol protease with a single, N-glycosylated polypeptide chain as a model to investigate the role of glycosylation of proteins. Periodate oxidation was used to obtain the deglycosylated form of the enzyme. Denaturation studies in the presence of guanidine hydrochloride (Gn*HCl) were performed using fluorescence and circular dichroism spectroscopy. The glycosylated stem bromelain was found to be stabilized by 1.9 kcal/mol as compared to the deglycosylated one. At a given concentration of denaturant, the fraction of denatured protein was higher in the case of deglycosylated stem bromelain. In short, deglycosylated bromelain showed more susceptibility towards guanidine hydrochloride denaturation, indicating the contribution of the carbohydrate part of the glycoprotein to the stability of the enzyme.
Rasheedi
Sheeba
S
Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202 002, India.
Haq
Soghra Khatun
SK
Khan
Rizwan Hasan
RH
D031230:Ananas; D001963:Bromelains / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D006031:Glycosylation; D019791:Guanidine / Q000494:pharmacology*; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D013050:Spectrometry, Fluorescence
D001963:Bromelains; C091760:stem bromelain; D019791:Guanidine