Malena Granbom, Patrícia F. Lopes, Marianne Pedersén, Pio Colepicolo
Nitrate reductase in the marine macroalga Kappaphycus alvarezii (Rhodophyta): oscillation due to the protein level
Nitrate reductase (NR; EC 1.6.6.1) of the marine red macroalga Kappaphycus alvarezii was examined in algae maintained under L:D and constant light conditions. Undenaturated protein had a molecular mass of about 210 kD (±23 kD); based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting techniques, the enzyme appears to be composed of two possibly identical subunits of 100 kD. The NR of K. alvarezii was recognized by 10 out of 17 monoclonal antibodies raised against the NR from the red alga Porphyra yezoensis. Basal parts of the algal thallus had higher NR protein content, although the highest activity of NR has been located previously in the apical thallus parts, suggesting a post-translational regulation. The cellular expression of NR exhibits a daily rhythm. In extracts of algae grown under either constant light or a light:dark cycle, staining with antibodies NR 6 and NR 10 showed that the amount of protein varied by a factor of about 2, with the maximum occurring in the early day phase.
Botanica Marina, Walter de Gruyter
Print ISSN: 0006-8055
Volume: 50, 07/2007
Pages: 106 - 112
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