Purification and Characterization of Dihydrodipicolinate Synthase from Wheat Suspension Cultures

Purification and Characterization of Dihydrodipicolinate Synthase from Wheat Suspension Cultures Dihydrodipicolinate synthase, the first enzyme unique to lysine biosynthesis in higher plants, was purified about 5100-fold from suspension-cultured cells of wheat ( Triticum aestivum var Chinese Spring). The synthase has an average molecular weight of 123,000 as determined by gel filtration and exhibited maximum activity at pH 8.0. The kinetics of the condensation reaction are compatible with a “Ping Pong” mechanism in which pyruvate reacts first with the enzyme to form a Schiff base. Pyruvate and l -aspartic-β-semialdehyde (ASA) have respective K m values of 11.76 and 0.80 millimolar. Allosteric inhibition was observed with increasing concentrations of l -lysine and its structural analogs, including threo -4-hydroxy- l -lysine and S -(2-aminoethyl)- l -cysteine, with respective I 0.5 values of 51, 141, and 288 micromolar. These amino acids were competitive inhibitors with respect to ASA and noncompetitive inhibitors with respect to pyruvate. We propose that the binding site for lysine overlaps with the ASA binding site, possibly by an attachment of the common alanyl moiety. The wheat enzyme was inhibited by Zn 2+ , Cd 2+ , and Hg 2+ and also by sulfhydryl inhibitors, p -(hydroxymercuri)benzoic acid and p -chloromercuribenzenesulfonic acid. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

Purification and Characterization of Dihydrodipicolinate Synthase from Wheat Suspension Cultures

Loading next page...
 
/lp/american-society-of-plant-biologist/purification-and-characterization-of-dihydrodipicolinate-synthase-from-3xOTyWHdvh
Publisher
American Society of Plant Biologist
Copyright
Copyright © 1987 by the American Society of Plant Biologists
ISSN
1532-2548
eISSN
0032-0889
D.O.I.
10.1104/pp.85.1.145
Publisher site
See Article on Publisher Site

Abstract

Dihydrodipicolinate synthase, the first enzyme unique to lysine biosynthesis in higher plants, was purified about 5100-fold from suspension-cultured cells of wheat ( Triticum aestivum var Chinese Spring). The synthase has an average molecular weight of 123,000 as determined by gel filtration and exhibited maximum activity at pH 8.0. The kinetics of the condensation reaction are compatible with a “Ping Pong” mechanism in which pyruvate reacts first with the enzyme to form a Schiff base. Pyruvate and l -aspartic-β-semialdehyde (ASA) have respective K m values of 11.76 and 0.80 millimolar. Allosteric inhibition was observed with increasing concentrations of l -lysine and its structural analogs, including threo -4-hydroxy- l -lysine and S -(2-aminoethyl)- l -cysteine, with respective I 0.5 values of 51, 141, and 288 micromolar. These amino acids were competitive inhibitors with respect to ASA and noncompetitive inhibitors with respect to pyruvate. We propose that the binding site for lysine overlaps with the ASA binding site, possibly by an attachment of the common alanyl moiety. The wheat enzyme was inhibited by Zn 2+ , Cd 2+ , and Hg 2+ and also by sulfhydryl inhibitors, p -(hydroxymercuri)benzoic acid and p -chloromercuribenzenesulfonic acid.

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off