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Investigations of interesting enzyme...

Udwary, Daniel W.

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Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis./
Author:	Udwary, Daniel W.
Description:	158 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-02, Section: B, page: 0702.
Contained By:	Dissertation Abstracts International64-02B.
Subject:	Chemistry, Biochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3080784
ISBN:	0496286590

Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis.
Udwary, Daniel W.

Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis. - 158 p.

Source: Dissertation Abstracts International, Volume: 64-02, Section: B, page: 0702.

Thesis (Ph.D.)--The Johns Hopkins University, 2003.

The biosynthesis of the Aspergillus parasiticus toxin aflatoxin B1 is a long and complicated process involving at least 15 enzyme-mediated reactions. While most of the genes involved have been identified and their functions assigned, few of the details of the enzymology of these reactions have been described. This thesis describes the investigations of the proteins involved in biosynthesis of the first aflatoxin precursor, norsolorinic acid, as well as the cytochromes P450 involved in the complex anthraquinone to xanthone to coumarin carbon skeleton rearrangements that occur in the final stages of the pathway. In attempting to discern the locations of domains of the polyketide and fatty acid synthases responsible for the synthesis of norsolorinic acid we have developed a general method, called UMA, for sequence-based detection of domains in families of multifunctional proteins. Predictions made by UMA compare favorably to structurally characterized proteins, and are applied to a "dissection" of the polyketide and fatty acid synthases. Heterologous expression of the cytochrome P450 OrdA in a S. cerevisiae membrane preparation enabled the detection of 11-hydroxy O-methylsterigmatocystin as an intermediate in the conversion of O-methylsterigmatocystin to aflatoxin B1. The A. parasiticus cytochrome P450 reductase, a coenzyme needed for transfer of electrons to eukaryotic cytochromes P450, was isolated and sequenced, and should prove useful for future studies of A. parasiticus cytochromes P450. The enzymes responsible for conversion of versicolorin A to demethylsterigmatocystin were examined and a proposal for their interaction and mechanism of action is put forth.

ISBN: 0496286590Subjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis.
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245 1 0 $a Investigations of interesting enzymes in the early and late stages of aflatoxin biosynthesis.
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500 $a Source: Dissertation Abstracts International, Volume: 64-02, Section: B, page: 0702.
500 $a Adviser: Craig A. Townsend.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2003.
520 $a The biosynthesis of the Aspergillus parasiticus toxin aflatoxin B1 is a long and complicated process involving at least 15 enzyme-mediated reactions. While most of the genes involved have been identified and their functions assigned, few of the details of the enzymology of these reactions have been described. This thesis describes the investigations of the proteins involved in biosynthesis of the first aflatoxin precursor, norsolorinic acid, as well as the cytochromes P450 involved in the complex anthraquinone to xanthone to coumarin carbon skeleton rearrangements that occur in the final stages of the pathway. In attempting to discern the locations of domains of the polyketide and fatty acid synthases responsible for the synthesis of norsolorinic acid we have developed a general method, called UMA, for sequence-based detection of domains in families of multifunctional proteins. Predictions made by UMA compare favorably to structurally characterized proteins, and are applied to a "dissection" of the polyketide and fatty acid synthases. Heterologous expression of the cytochrome P450 OrdA in a S. cerevisiae membrane preparation enabled the detection of 11-hydroxy O-methylsterigmatocystin as an intermediate in the conversion of O-methylsterigmatocystin to aflatoxin B1. The A. parasiticus cytochrome P450 reductase, a coenzyme needed for transfer of electrons to eukaryotic cytochromes P450, was isolated and sequenced, and should prove useful for future studies of A. parasiticus cytochromes P450. The enzymes responsible for conversion of versicolorin A to demethylsterigmatocystin were examined and a proposal for their interaction and mechanism of action is put forth.
590 $a School code: 0098.
650 4 $a Chemistry, Biochemistry. $3 1017722
650 4 $a Chemistry, Organic. $3 516206
650 4 $a Biophysics, General. $3 1019105
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