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The mechanism of the thiamin diphosp...

The Johns Hopkins University.

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The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase./
作者:	Merski, Matthew.
面頁冊數:	255 p.
附註:	Adviser: Craig A. Townsend.
Contained By:	Dissertation Abstracts International68-12B.
標題:	Biophysics, General. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3295798
ISBN:	9780549404033

The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase.
Merski, Matthew.

The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase. - 255 p.

Adviser: Craig A. Townsend.

Thesis (Ph.D.)--The Johns Hopkins University, 2008.

Clavulanic acid is a naturally-occurring inhibitor of beta-lactamase enzymes. Its importance in clinical medicine has increased steadily as resistance to antibiotic therapy has continued its inevitable, ominous rise. Bacterial resistance to widely used penams and cephems owes typically to plasmid encoded beta-lactamases that efficiently hydrolyze these antibiotics rendering them ineffective. Combinations of clavulanic acid and, for example, amoxycillin (i.e. Augmentin(TM)) have greatly extended the usefulness of penicillins in an era of increasingly resistant infections.

ISBN: 9780549404033Subjects--Topical Terms:

1019105
Biophysics, General.

The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase.
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100 1 $a Merski, Matthew. $3 1023445
245 1 4 $a The mechanism of the thiamin diphosphate-dependent enzyme carboxyethylarginine synthase.
300 $a 255 p.
500 $a Adviser: Craig A. Townsend.
500 $a Source: Dissertation Abstracts International, Volume: 68-12, Section: B, page: 7865.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2008.
520 $a Clavulanic acid is a naturally-occurring inhibitor of beta-lactamase enzymes. Its importance in clinical medicine has increased steadily as resistance to antibiotic therapy has continued its inevitable, ominous rise. Bacterial resistance to widely used penams and cephems owes typically to plasmid encoded beta-lactamases that efficiently hydrolyze these antibiotics rendering them ineffective. Combinations of clavulanic acid and, for example, amoxycillin (i.e. Augmentin(TM)) have greatly extended the usefulness of penicillins in an era of increasingly resistant infections.
520 $a The first dedicated step in biosynthesis of clavulanic acid is catalyzed by N2-carboxyethyl arginine synthase (CEAS). In this reaction two intermediates from primary cellular metabolism, D-glyceraldehyde-3-phosphate (G3P) and L-arginine are linked in an atypical thiamin diphosphate (ThDP) cofactor mediated process to synthesize N2-carboxyethyl arginine (CEA). An internal redox reaction is catalyzed to convert G3P to a highly electrophilic acrylic acid derivative, which then undergoes beta-addition by the alpha-nitrogen of L-arginine followed by hydrolysis to liberate the product. This C-N bond formation is unique to CEAS among ThDP-dependent enzymes. We have observed a strongly red-shifted absorbance band (ca. 25 kcal/mol) in CEAS that correlates with the "Ping" state of the enzyme. Formation of the band is intimately tied to an active site histidinium residue, whose behavior is modulated by a hydrogen-bonded arginine.
520 $a Formation of this chromophoric intermediate has been shown to correspond to increased enzymatic activity. Noticeably, the essential histidine residue is structurally conserved in all the ThDP enzymes which catalyze reactions involving polar intermediates regardless of the cationic or anionic nature of these intermediates. The spectroscopic and kinetic effects are attributed to polarizability of the thiamin-intermediate adduct and to the presence of diffuse proximal charge density.
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