Structure of the dinuclear active site of urease. X-ray absorption spectroscopic study of native and 2-mercaptoethanol-inhibited bacterial and plant enzymes

Journal Article · Wed Apr 13 04:00:00 EDT 1994 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00086a006· OSTI ID:7102028

Wang, Shengke; Scott, R A ^[1]; Lee, M H; Hausinger, R P ^[2]; Clark, P A; Wilcox, D E ^[3]

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1. Univ. of Georgia, Athens (United States)
2. Michigan State Univ., East Lansing (United States)
3. Dartmouth College, Hanover, NH (United States)

The structures of the dinuclear Ni(II) active sites of urease from jack bean and Klebsiella aerogenes are compared with and without the addition of the inhibitor 2-mercaptoethanol (2-ME). No significant differences are observed by nickel K-edge X-ray absorption spectroscopy between the plant and bacterial enzymes. The Ni X-ray absorption edge spectra display an 8332-eV 1s[yields]3d peak intensity similar to that observed for five-coordinate Ni(II) compounds[sup 1] for both native and 2-ME-bound derivatives. Curve-fitting of Ni EXAFS data indicates that the average Ni(II) coordination environment in native urease can be described as Ni(imidazole)[sub x](N,O)[sub 5[minus]x], with x = 2 or 3. Addition of 2-ME results in replacement of one of the non-imidazole (N,O) ligands with (S,Cl) (most likely the thiolate sulfur of 2-ME) and results in the appearance of a new peak in the Fourier transforms that can only be fit with a Ni[center dot][center dot][center dot]Ni scattering component at a Ni-Ni distance of [approximately]3.26 [angstrom]. A structure for this 2-ME-bound dinuclear site is proposed to contain the two Ni(II) ions bridged by the thiolate sulfur of 2-ME.

• OSTI ID: 7102028
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 33:8; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
AMIDINASES
BACTERIA
BEANS
COMPLEXES
ENZYME INHIBITORS
ENZYMES
FOOD
HYDROLASES
MICROORGANISMS
NICKEL COMPLEXES
NON-PEPTIDE C-N HYDROLASES
ORGANIC COMPOUNDS
PLANTS
PROTEINS
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPLEXES
UREASE
VEGETABLES
X-RAY SPECTROSCOPY