Journal Article

An NADP-Glutamate Dehydrogenase from the Green Alga <i>Bryopsis maxima</i>. Purification and Properties

Ritsuko Inokuchi, Tadashi Itagaki, Joseph T. Wiskich, Katsumi Nakayama and Mitsumasa Okada

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 38, issue 3, pages 327-335
Published in print January 1997 | ISSN: 0032-0781
Published online January 1997 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029170
An NADP-Glutamate Dehydrogenase from the Green Alga Bryopsis maxima. Purification and Properties

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

NADP-glutamate dehydrogenase (EC 1.4.1.4; NADP-GDH) was purified to electrophoretic homogeneity from the multinuclear-unicellular green marine alga in Sipho-nales, Bryopsis maxima, and its properties were examined. Mr of the undenatured enzyme was 280 kDa, and the enzyme is thought to be a hexamer of 46 kDa subunit protein. Optimum pHs for the reductive amination and oxidative deamination were 7.5 and 8.2-9.0 respectively. The enzyme displayed NADPH/NADH-specific activities with a ratio of 18 :1. Apparent Km values for 2-oxoglutarate, ammonia, NADPH, glutamate and NADP+ were 3.0, 2.2, 0.03, 3.2 and 0.01 mM respectively. The enzymochemical characteristics of the GDH were studied and compared to those of other species. The B. maxima GDH was insensitive to 5 mM Ca2+ and to 1 mM EDTA in contrast to higher plant NAD-GDHs. Chemical modifications with DTNB and pCMBS suggested that cysteine residues are essential for the enzymatic activity as in other species GDHs. The GDH was not affected by 1 mM purine nucleotides, suggesting that the enzyme is not allosteric, in contrast to animal NAD(P)-GDHs and fungal NAD-GDHs.

Keywords: Ammonia assimilation; Bryopsis maxima; Glutamate dehydrogenase (EC 1.4.1.4); GS-GOGAT cycle; NADP

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.