title: Effect of mammalian kidney osmolytes on the folding pathway of sheep serum albumin.
abstract: Recently, we had published that urea-induced denaturation curves of optical properties of sheep serum albumin (SSA) are biphasic with a stable intermediate that has characteristics of molten globule (MG) state. In this study, we have extended the work by carrying out urea- and guanidinium chloride (GdmCl)-induced denaturations of SSA in the presence of naturally occurring mammalian kidney osmolytes, namely, sorbitol, myo-inositol and glycine betaine. We have observed that all these osmolytes (i) transform this biphasic transition into a co-operative, two-state transition and (ii) increase the stability of the protein in terms of midpoint of denaturation (Cm) and Gibbs free energy change in the absence of both denaturants (ΔGD0). The relative effectiveness of different osmolytes on the stability of SSA follows the order: glycine betaine>myo-inositol>sorbitol. In this paper, we also report that kidney osmolytes destabilize MG state by shifting the equilibrium, native state↔MG state toward the left. This study will be helpful in understanding the existence of osmolytes in kidney and their role in folding of kidney proteins soaked with urea.
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India.
authors.forename: Mohammad Aasif
authors.initials: MA
authors.lastname: Dar
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India. Electronic address: aislam@jmi.ac.in.
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India.
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India. Electronic address: fahmad@jmi.ac.in.
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
mesh_terms: D000818:Animals; D001622:Betaine / Q000494:pharmacology; D019791:Guanidine / Q000494:pharmacology; D007294:Inositol / Q000494:pharmacology; D007668:Kidney; D009995:Osmosis; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects*; D055550:Protein Stability / Q000187:drug effects; D012709:Serum Albumin / Q000737:chemistry*; D012756:Sheep; D013012:Sorbitol / Q000494:pharmacology; D013816:Thermodynamics; D014508:Urea / Q000494:pharmacology
chemical_list: D012709:Serum Albumin; D001622:Betaine; D007294:Inositol; D013012:Sorbitol; D014508:Urea; D019791:Guanidine
keywords: Guanidinium chloride denaturation; Kidney osmolytes; Sheep serum albumin; Three-state denaturation; Two-state denaturation; Urea denaturation