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Characterization of paramagnetic int...

Mansoorabadi, Steven Omid.

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Characterization of paramagnetic intermediates in enzymatic reactions.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Characterization of paramagnetic intermediates in enzymatic reactions./
作者:	Mansoorabadi, Steven Omid.
面頁冊數:	211 p.
附註:	Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3119.
Contained By:	Dissertation Abstracts International67-06B.
標題:	Chemistry, Biochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3222835
ISBN:	9780542753305

Characterization of paramagnetic intermediates in enzymatic reactions.
Mansoorabadi, Steven Omid.

Characterization of paramagnetic intermediates in enzymatic reactions. - 211 p.

Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3119.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2006.

Paramagnetic intermediates in the reactions catalyzed by the enzymes pyruvate:ferredoxin oxidoreductase (PFOR), methylmalonyl-CoA mutase (MCM), and diol dehydrase (DDH) were characterized by a combination of spectroscopic and computational approaches.

ISBN: 9780542753305Subjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Characterization of paramagnetic intermediates in enzymatic reactions.
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100 1 $a Mansoorabadi, Steven Omid. $3 1920642
245 1 0 $a Characterization of paramagnetic intermediates in enzymatic reactions.
300 $a 211 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3119.
500 $a Adviser: George H. Reed.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2006.
520 $a Paramagnetic intermediates in the reactions catalyzed by the enzymes pyruvate:ferredoxin oxidoreductase (PFOR), methylmalonyl-CoA mutase (MCM), and diol dehydrase (DDH) were characterized by a combination of spectroscopic and computational approaches.
520 $a The radical intermediate of PFOR was analyzed using EPR spectroscopy at X-band and D-band microwave frequencies. EPR spectra obtained with isotopically labeled substrate and coenzyme were simulated and the parameters obtained were compared with those predicted from electronic structure calculations. The data are consistent with a planar, HE-TPP pi-radical, in which the pyruvate-derived oxygen atom forms a H-bond. The parameters are not compatible with a non-planar, sigma/n-type cation radical. Pulsed EPR methods were used to measure the distance between the HE-TPP radical and the [4Fe-4S]1+ cluster to which it is coupled. Computational analysis demonstrated that the distance between the HE-TPP radical and the medial cluster B matches the experimentally determined dipolar interaction.
520 $a An intermediate freeze trapped in the steady state of MCM was analyzed by EPR spectroscopy. The spectrum is due to a hybrid triplet spin system comprised of an organic radical and cob(II)alamin. The spectrum was analyzed by simulation to obtain the ZFS parameters and Euler angles relating the interspin vector to the g-axis system of Co2+. Inhomogeneous broadening by 13C and 2H from labeled substrates identified the organic radical as the succinyl-CoA product radical. The simulation parameters were used to position the radical into the active site of MCM.
520 $a A triplet spin system was detected by low-temperature EPR in samples of DDH with 5'-deoxy-3',4'-anhydroadenosylcobalamin (anAdoCbl). Different spectra are observed in the presence and absence of the substrate. 59Co-hyperfine splitting, the resonant field values and linewidth effects from isotopic labeling (13C and 2H) in the coenzyme demonstrate that the spectrum from an anhydroadenosyl radical-cob(II)alamin triplet system. These EPR spectra were simulated and the ZFS tensors were analyzed using a point charge approximation to position the anhydroadenosyl radical in the active site of DDH. These results provide spectroscopic support for the intermediacy of the 5'-deoxyadenosyl radical. Homolytic cleavage of anAdoCbl in the absence of substrate indicates that binding of the coenzyme to DDH weakens the bond prior to binding of substrate.
590 $a School code: 0262.
650 4 $a Chemistry, Biochemistry. $3 1017722
650 4 $a Biophysics, General. $3 1019105
690 $a 0487
690 $a 0786
710 2 0 $a The University of Wisconsin - Madison. $3 626640
773 0 $t Dissertation Abstracts International $g 67-06B.
790 1 0 $a Reed, George H., $e advisor
790 $a 0262
791 $a Ph.D.
792 $a 2006
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