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Mechanistic details of class A and c...

Golemi-Kotra, Dasantila.

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Mechanistic details of class A and class D beta-lactamases.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Mechanistic details of class A and class D beta-lactamases./
Author:	Golemi-Kotra, Dasantila.
Description:	158 p.
Notes:	Adviser: Shahriar Mobashery.
Contained By:	Dissertation Abstracts International63-03B.
Subject:	Biology, Microbiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3047553
ISBN:	0493620435

Mechanistic details of class A and class D beta-lactamases.
Golemi-Kotra, Dasantila.

Mechanistic details of class A and class D beta-lactamases. - 158 p.

Adviser: Shahriar Mobashery.

Thesis (Ph.D.)--Wayne State University, 2002.

Bacteria find themselves always threaten by the surrounding environment. To survive, they have evolved many protecting mechanisms. The extensive use of antibiotics in everyday life has put bacteria under a higher pressure. Taking advantage of their rapid multiplication (every 20 min they duplicate) and intrinsic errors in DNA replication, bacteria have evolved mechanisms to coexist in the face of many classes of antibiotics discovered by humans. To date, resistance mechanisms toward all the classes of antibiotics have been encountered. It is clear that in order to stay ahead of bacteria we have to understand in molecular level the resistance mechanisms. Expression of the β-lactamases is the most common resistance mechanism against β-lactam antibiotics, they hydrolyze these antibiotics before they reach their target. It is interesting that four mechanisms have been evolved to hydrolyze the β-lactam antibiotics. TEM β-lactamases are often found in clinical isolates conferring resistance to many antibiotics such as penicillins, cephalosporins as well the clinically used inhibitors clavulanate, sulbactam, and tazobactam. These enzymes are variants of TEM-1 β-lactamase, they differ from wild-type from one or more point mutations. Through the work at Mobashery Lab we have found that it does not take much for the enzyme to evolve resistance to a β-lactam antibiotics or the clinically used inhibitors. Subtle electrostatic and/or structural alterations in the active site of the enzyme result inhibitor-resistance traits. Furthermore, we have shown that the class D OXA-10 β-lactamase has evolved a distinct mechanism for its reaction compared to other β-lactamases. This enzyme depends on a critical carbamylated lysine in the active site for its catalytic mechanism. This finding suggests that disparate classes of β-lactamases have pursued different mechanisms to carry out the same reaction and nature finds means to expand the catalytic capabilities of the amino acids in proteins beyond the 20 common amino acids in development of the biological catalyst.

ISBN: 0493620435Subjects--Topical Terms:

1017734
Biology, Microbiology.

Mechanistic details of class A and class D beta-lactamases.
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100 1 $a Golemi-Kotra, Dasantila. $3 1259045
245 1 0 $a Mechanistic details of class A and class D beta-lactamases.
300 $a 158 p.
500 $a Adviser: Shahriar Mobashery.
500 $a Source: Dissertation Abstracts International, Volume: 63-03, Section: B, page: 1344.
502 $a Thesis (Ph.D.)--Wayne State University, 2002.
520 $a Bacteria find themselves always threaten by the surrounding environment. To survive, they have evolved many protecting mechanisms. The extensive use of antibiotics in everyday life has put bacteria under a higher pressure. Taking advantage of their rapid multiplication (every 20 min they duplicate) and intrinsic errors in DNA replication, bacteria have evolved mechanisms to coexist in the face of many classes of antibiotics discovered by humans. To date, resistance mechanisms toward all the classes of antibiotics have been encountered. It is clear that in order to stay ahead of bacteria we have to understand in molecular level the resistance mechanisms. Expression of the β-lactamases is the most common resistance mechanism against β-lactam antibiotics, they hydrolyze these antibiotics before they reach their target. It is interesting that four mechanisms have been evolved to hydrolyze the β-lactam antibiotics. TEM β-lactamases are often found in clinical isolates conferring resistance to many antibiotics such as penicillins, cephalosporins as well the clinically used inhibitors clavulanate, sulbactam, and tazobactam. These enzymes are variants of TEM-1 β-lactamase, they differ from wild-type from one or more point mutations. Through the work at Mobashery Lab we have found that it does not take much for the enzyme to evolve resistance to a β-lactam antibiotics or the clinically used inhibitors. Subtle electrostatic and/or structural alterations in the active site of the enzyme result inhibitor-resistance traits. Furthermore, we have shown that the class D OXA-10 β-lactamase has evolved a distinct mechanism for its reaction compared to other β-lactamases. This enzyme depends on a critical carbamylated lysine in the active site for its catalytic mechanism. This finding suggests that disparate classes of β-lactamases have pursued different mechanisms to carry out the same reaction and nature finds means to expand the catalytic capabilities of the amino acids in proteins beyond the 20 common amino acids in development of the biological catalyst.
590 $a School code: 0254.
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650 4 $a Chemistry, Biochemistry. $3 1017722
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