Purification and Characterization of Mannitol-l-Phosphatase in the Red Alga Caloglossa continua (Ceramiales, Rhodophyta)
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Purification of mannitol-l-phosphatase, an enzyme catalyzing the final step of mannitol biosynthesis, was first achieved in the mannitol-accumulating red alga Caloglossa continua (Okamura) King et Puttock. The enzyme was shown to be a monomer, since gel filtration and sodium dodecyl sulfate–polyacrylamide gel electrophoresis gave close values of apparent molecular weights of 28,500 and 30,200, respectively. The protein exhibited an isoelectric point of 4.8. The substrate specificity for mannitol-l-phosphate (MIP) was very high, and that for K m(MIP) was 0.41 mM. The catalytic activity was optimal at pH 7.4. The enzyme was activated by Mg2+, but was strongly inhibited by Ca2+, NaF, N-ethylmaleimide, and p-hydroxymercuribenzoic acid. Seawater levels of NaCl and physiological levels of mannitol also inhibited the activity by 50% or more. Changes in the concentrations of those ions and metabolites may regulate the biosynthesis of mannitol as an osmoregulant in vivo.
- Purification and Characterization of Mannitol-l-Phosphatase in the Red Alga Caloglossa continua (Ceramiales, Rhodophyta)
Volume 3, Issue 5 , pp 493-500
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- Key words:Caloglossa continua, enzyme purification, mannitol biosynthesis, mannitol-l-phosphatase, red alga, salt stress.
- Author Affiliations
- A1. Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan, JP
- A2. Faculty of Education and Human Studies, Akita University, Tegata-gakuen, Akita 010-8502, Japan, JP
- A3. Faculty of Management and Information Sciences, Jobu University, Shinmachi, Gunma 370-1393, Japan, JP