Studies on enzymatic reactions /

()︢-(15E)&(15Z)-16-oxa-2,3-oxidosqualenes were successfully

Bibliographic Details
Main Author:	Park, Jeong Ho, 1964-
Format:	Thesis Book
Language:	English
Published:	[Place of publication not identified] : [publisher not identified] ; 1996.
Subjects:	Major chemistry.
Online Access:	http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739364001&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD

Description
Summary:	()︢-(15E)&(15Z)-16-oxa-2,3-oxidosqualenes were successfully synthesized through the Wittig-Homer reaction as postulated trapping agents of a C-ring intermediate of 2,3-oxidosqualene cyclases (OSC). The mechanistic study of C-ring formation was negative with this substrate, due to the instability of the enol ether under the incubationconditions. Expression of HBA a,c-diamide synthetase (cobb) was attempted in E. coli by constructing several recombinant plasmids in order to accomplish the enzymatic one-pot reaction from starting materials (ALA) to the desired product (vitamin B 12) by adding essential enzymes and cofactors. The activity of the cobb expressed from cells harboring recombinant pliasmids was negative in all systems. The problem of product inhibition in E. coli SAM synthetase (metk) was overcome by including additives such as bME, acetonitrile, urea, or pTsONa. A recombinant strain of E. coli has been constructed for the expression of yeast SAM synthetase encoded by the sam2 gene to solve the problem of product inhibition existing in native E. coli. Complete conversion of 10 mM methionine to SAM was achieved in incubations either with recombinant yeast SAM synthetase by addition of t molar potassium ion or with E. coli SAM synthetase in the presence of additives such as bME, acetonitrile, urea, or pTsONa.
Item Description:	Vita. "Major Subject: Chemistry".
Physical Description:	xi, 125 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc.
Bibliography:	Includes bibliographical references: pages 109-122.