Lancaster EPrints

Degradation of lysine in rice seeds : effects of calcium, ionic strength, S-adenosylmethionine and S-2-aminoethyl-L-cysteine on lysine 2-oxoglutarate reductase-saccharopine dehydrogenase bifunctional enzyme.

Gaziola, S. A. and Sodek, L. and Arruda, P. and Lea, P. J. and Azevedo, R. A. (2000) Degradation of lysine in rice seeds : effects of calcium, ionic strength, S-adenosylmethionine and S-2-aminoethyl-L-cysteine on lysine 2-oxoglutarate reductase-saccharopine dehydrogenase bifunctional enzyme. Physiologia Plantarum, 110 (2). pp. 164-171. ISSN 0031-9317

Full text not available from this repository.

Abstract

Lysine biosynthesis has been extensively studied and the regulatory enzymes characterized in some of the most important crop plants, however, much less is known about the lysine degradation pathway. Lysine 2-oxoglutarate reductase (LOR) and saccharopine dehydrogenase (SDH) have recently been partially purified and characterized from plants, and have been shown to exist as a single bifunctional polypeptide. We have further characterized these enzymes from rice endosperm in relation to Ca2+ and ionic strength modulation. Optimum pH values of 7.0 and 8.0 were obtained for LOR and SDH, respectively. The LOR domain of the polypeptide was modulated by Ca2+ and ionic strength, whereas the SDH domain was not. It would appear that the modulation by Ca2+ and ionic strength of LOR is a common feature among plant LOR enzymes. S-adenosylmethionine (SAM) did not produce any significant effect on either enzyme activity, indicating that it only plays a role in the regulation of lysine biosynthesis. The effect of S-2-aminoethyl- l-cysteine (AEC) as both a substrate and an inhibitor of LOR activity was also tested. AEC was shown to partially substitute for lysine as a substrate for LOR, but was also able to inhibit LOR activity, possibly competing with lysine at the active site. The higher Km for AEC compared to lysine may reflect a lower binding affinity for AEC.

Item Type: Article
Journal or Publication Title: Physiologia Plantarum
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 10858
Deposited By: Mr Richard Ingham
Deposited On: 25 Jul 2008 11:20
Refereed?: Yes
Published?: Published
Last Modified: 09 Apr 2014 20:19
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/10858

Actions (login required)

View Item