title: Sodium-23 and lanthanum-139 nuclear magnetic resonance studies of cation binding to aqualysin I, a thermostable serine protease.
abstract: Aqualysin I has at least two Ca2+-binding sites that have different affinities for Ca2+. The binding of various metal ions to aqualysin I was studied using 23Na- and 139La-NMR spectrometry. Evidence is presented that Ca2+, La3+, and Na+ bind to the low-affinity Ca2+-binding site of aqualysin I, but Mg2+ does not. Our results confirm that binding of metals at the low-affinity Ca2+-binding site is essential for thermostabilization, since the addition of Mg2+ did not result in thermostabilization. La3+ was found to bind to both the low-affinity Ca2+-binding site and an additional metal ion-binding site that can also be involved in the thermostabilization of aqualysin I.
authors.affiliation: Department of Biotechnology, The University of Tokyo, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Suefuji
authors.forename: Shie-Jea
authors.initials: SJ
authors.lastname: Lin
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Wakagi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuzawa
authors.forename: Etsuro
authors.initials: E
authors.lastname: Yoshimura
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002412:Cations / Q000737:chemistry / Q000378:metabolism; D004795:Enzyme Stability; D020035:Holoenzymes / Q000737:chemistry / Q000378:metabolism; D007811:Lanthanum / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D012964:Sodium / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
chemical_list: D002412:Cations; D020035:Holoenzymes; D008670:Metals; D007811:Lanthanum; D012964:Sodium; D012697:Serine Endopeptidases; C055102:aqualysin I; D008274:Magnesium; D002118:Calcium