This application is concerned with further elucidating the chemistry of halide-activating peroxidase enzymes. Studies will focus on defining the active site molecular structure, the electronic structure, and the reactivity properties of lactoperoxidase and chloroperoxidase. Emphasis will be placed on nuclear magnetic resonance (NMR) spectrocopy of the hemoproteins, as well as synthesis and reactions of appropriate iron porphyrin model compounds. The importance of this work is found in the observation that major classes of mammalian peroxidases exert their biosynthetic or biological defense functions through activation of halide or pseudohalide ions. Particular attention will be given to elucidating the chemistry of lactoperoxidase-thiocynate interactions, as this system functions to protect exocrine fluids from bacterial invasion. Likewise, the chloride-activating bactericidal functions of leukocyte myeloperoxidase will be modeled by the microbial chloroperoxidase enzyme. Specific objectives follow: (1) electronic structures of lactoperoxidase and chloroperoxidase in various redox states will be better defined and compared with those of other hemoproteins through high-field NMR measurements; (2) the active site molecular structure will be probed through carbon-13 and nitrogen-15 NMR spectroscopy, of ligands (CO, NC-, SCN, and isonitriles) bound at the iron center, (3) non-heme anion binding sites will be probed through use of multinuclear NMR methods; and (4) attempts will be made to detect the direct products and discern the mechanisms of halide and pseudohalide activation in the peroxidases and in model heme compounds.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM028831-06S1
Application #
3276145
Study Section
Metallobiochemistry Study Section (BMT)
Project Start
1980-08-01
Project End
1986-11-30
Budget Start
1986-08-01
Budget End
1986-11-30
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Arts and Sciences
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Crull, G B; Goff, H M (1993) NMR relaxation studies of the interaction of thiocyanate with lactoperoxidase. J Inorg Biochem 50:181-92
Lukat, G S; Doran, M B; Utschig, L M et al. (1993) Magnetic resonance spectroscopy, calcium content, and anion coordination studies of bovine and goat lactoperoxidase. J Inorg Biochem 50:157-71
Dugad, L B; Wang, X; Wang, C C et al. (1992) Proton nuclear Overhauser effect study of the heme active site structure of chloroperoxidase. Biochemistry 31:1651-5
Pollock, J R; Goff, H M (1992) Lactoperoxidase-catalyzed oxidation of thiocyanate ion: a carbon-13 nuclear magnetic resonance study of the oxidation products. Biochim Biophys Acta 1159:279-85
Dugad, L B; Goff, H M (1992) Proton nuclear Overhauser effect study of the heme active site structure of Coprinus macrorhizus peroxidase. Biochim Biophys Acta 1122:63-9
Dugad, L B; Goff, H M; Abeles, F B (1991) 1H-NMR characterization of cucumber peroxidases. Biochim Biophys Acta 1118:36-40
Lukat, G S; Goff, H M (1990) A nuclear magnetic resonance study of axial ligation for the reduced states of chloroperoxidase, cytochrome P-450cam, and porphinatoiron(II) thiolate complexes. Biochim Biophys Acta 1037:351-9
Lukat, G S; Rodgers, K R; Jabro, M N et al. (1989) Magnetic resonance spectral characterization of the heme active site of Coprinus cinereus peroxidase. Biochemistry 28:3338-45
Lukat, G S; Jabro, M N; Rodgers, K R et al. (1988) Electron paramagnetic resonance spectroscopy of thyroid peroxidase. Biochim Biophys Acta 954:265-70
Lukat, G S; Rodgers, K R; Goff, H M (1987) Electron paramagnetic resonance spectroscopy of lactoperoxidase complexes: clarification of hyperfine splitting for the NO adduct of lactoperoxidase. Biochemistry 26:6927-32

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