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Structure function studies on the dimethyl sulfoxide reductase family of molybdopterin enyzmes

Record Type:	Electronic resources : Monograph/item
Title/Author:	Structure function studies on the dimethyl sulfoxide reductase family of molybdopterin enyzmes
Author:	Nelson, Kimberly Johnson.
Description:	138 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1849.
Notes:	Supervisor: K. V. Rajagopalan.
Contained By:	Dissertation Abstracts International65-04B.
Subject:	Chemistry, Biochemistry.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3129071
ISBN:	0496763318

Structure function studies on the dimethyl sulfoxide reductase family of molybdopterin enyzmes
Nelson, Kimberly Johnson.

Structure function studies on the dimethyl sulfoxide reductase family of molybdopterin enyzmes [electronic resource] - 138 p.

Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1849.

Thesis (Ph.D.)--Duke University, 2003.

Cloning and purification of E. coli TMAOR permitted clarification of the catalytic role of the different Mo-coordination geometries previously observed in DMSOR and provided the first structure of a substrate bound Mo(IV) center. A Tyr residue in the active site of DMSOR and BSOR that is missing in TMAOR was implicated in the ability of DMSOR and BSOR, unlike TMAOR, to utilize S-oxides. This residue is also essential for the ability of DMSOR to be reduced by dimethyl sulfide.

ISBN: 0496763318Subjects--Topical Terms:

226900
Chemistry, Biochemistry.

Structure function studies on the dimethyl sulfoxide reductase family of molybdopterin enyzmes
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300 $a 138 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1849.
500 $a Supervisor: K. V. Rajagopalan.
502 $a Thesis (Ph.D.)--Duke University, 2003.
520 # $a Cloning and purification of E. coli TMAOR permitted clarification of the catalytic role of the different Mo-coordination geometries previously observed in DMSOR and provided the first structure of a substrate bound Mo(IV) center. A Tyr residue in the active site of DMSOR and BSOR that is missing in TMAOR was implicated in the ability of DMSOR and BSOR, unlike TMAOR, to utilize S-oxides. This residue is also essential for the ability of DMSOR to be reduced by dimethyl sulfide.
520 # $a R. sphaeroides BSOR is the only molybdopterin-containing protein that utilizes NADPH as the direct electron donor to the Mo center. Stopped-flow spectrophotometry indicated that BSOR reduction by NADPH is faster than steady-state turnover and occurs with no indication of a Mo(V) intermediate species. Since no crystallographic structure is available for BSOR, a structure was modeled using R. sphaeroides DMSOR and S. massilia TMAOR structures as templates. This allowed a potential NADPH-binding site to be identified and confirmed by site-directed mutagenesis. This binding site is located in the active-site funnel of BSOR where it can directly reduce the Mo center, supporting a direct hydride transfer mechanism from NADPH during BSOR reduction.
520 # $a R. sphaeroides DorC, the pentaheme c-type cytochrome that serves as the physiological electron donor to DMSOR, was cloned and expressed in E. coli. DorC is specifically oxidized in the presence of DMSOR. This is the first report of any kinetic rates for DorC oxidation by DMSOR, and these studies indicated that this step is much slower than DMSOR oxidation by DMSO. Experiments with various quinols indicate that DorC prefers quinols with low reduction potentials.
520 # $a Rhodobacter sphaeroides dimethyl sulfoxide reductase (DMSOR), Escherichia coli trimethylamine N-oxide reductase (TMAOR), and R. sphaeroides biotin sulfoxide reductase (BSOR) are members of a class of bacterial oxotransferases that contain the bis(molybdopterin guanine dinucleotide)molybdenum cofactor as their sole cofactor. Detailed mechanistic studies were undertaken to determine which amino acid residues are responsible for the striking differences in the physiological roles, electron donors, and substrate specificity displayed by these highly homologous enzymes.
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773 0 # $g 65-04B. $t Dissertation Abstracts International
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790 1 0 $a Rajagopalan, K. V., $e advisor
791 $a Ph.D.
792 $a 2003
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