title: Inactivation and unfolding of protein tyrosine phosphatase from Thermus thermophilus HB27 during urea and guanidine hydrochloride denaturation.
abstract: The effects of urea and guanidine hydrochloride (GdnHCl) on the activity, conformation and unfolding process of protein tyrosine phosphatase (PTPase), a thermostable low molecular weight protein from Thermus thermophilus HB27, have been studied. Enzymatic activity assays showed both urea and GdnHCl resulted in the inactivation of PTPase in a concentration and time-dependent manner. Inactivation kinetics analysis suggested that the inactivation of PTPase induced by urea and GdnHCl were both monophasic and reversible processes, and the effects of urea and GdnHCl on PTPase were similar to that of mixed-type reversible inhibitors. Far-ultraviolet (UV) circular dichroism (CD), Tryptophan and 1-anilinonaphthalene -8-sulfonic acid (ANS) fluorescence spectral analyses indicated the existence of a partially active and an inactive molten globule-like intermediate during the unfolding processes induced by urea and GdnHCl, respectively. Based on the sequence alignment and the homolog Tt1001 protein structure, we discussed the possible conformational transitions of PTPase induced by urea and GdnHCl and compared the conformations of these unfolding intermediates with the transient states in bovine PTPase and its complex structures in detail. Our results may be able to provide some valuable clues to reveal the relationship between the structure and enzymatic activity, and the unfolding pathway and mechanism of PTPase.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China; College of Biotechnology, Southwest University, Beibei, Chongqing, China.
authors.forename: Yejing
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China; College of Biotechnology, Southwest University, Beibei, Chongqing, China.
authors.forename: Huawei
authors.initials: H
authors.lastname: He
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Gao
authors.affiliation: College of Biotechnology, Southwest University, Beibei, Chongqing, China.
authors.forename: Shui
authors.initials: S
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing, China.
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Xia
mesh_terms: D000595:Amino Acid Sequence; D004789:Enzyme Activation / Q000187:drug effects; D019791:Guanidine / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011489:Protein Denaturation / Q000187:drug effects*; D017433:Protein Structure, Secondary / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D016963:Thermus thermophilus / Q000201:enzymology*; D014508:Urea / Q000494:pharmacology*
chemical_list: D014508:Urea; D017027:Protein Tyrosine Phosphatases; D019791:Guanidine