title: Native states of adenylate kinase are two active sub-ensembles.
abstract: There are two kinds of conformational forms of adenylate kinase (AK) in equilibrium in solution with different ANS-binding properties. Furthermore, the nature of AP(5)A inhibition suggests also that the native forms of AK for binding with different substrates pre-exist in the absence of substrates. In the present study, a kinetics approach was used to explore the native forms distinguished by ANS-binding properties and by the nature of AP(5)A inhibition. The results revealed that the native forms distinguished by ANS probe are two conformational sub-ensembles. Both sub-ensembles are active and consist of a series of forms, which pre-exist in solution and can bind with different substrates. The K(m) values of N(1) for AMP, ADP and MgATP are larger than that of N(2), indicating that the N(2) sub-ensemble is more specific for binding substrates. This is consistent with the previous observation that the activity of N(2) is about 1.8-fold of that of N(1).
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Han
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Xianming
authors.initials: X
authors.lastname: Pan
mesh_terms: D000263:Adenylate Kinase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D015226:Dinucleoside Phosphates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008954:Models, Biological; D011487:Protein Conformation; D017510:Protein Folding; D011817:Rabbits; D012996:Solutions; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D000817:Anilino Naphthalenesulfonates; D015226:Dinucleoside Phosphates; D004791:Enzyme Inhibitors; D012996:Solutions; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C027132:1-anilino-8-naphthalenesulfonate; D000263:Adenylate Kinase