Uptake and physiological function of vitamin B₁₂ in a photosynthetic unicellular coccolithophorid alga, Pleurochrysis carterae
2002
MIYAMOTO, Emi | Watanabe, Fumio | TAKENAKA, Hiroyuki | NAKANO, Yoshihisa
The photosynthetic coccolithophoid alga, Pleurochrysis (Hymenomonas) carterae, could take up and accumulate exogenous vitamin B₁₂, most of which was converted into the coenzyme forms of vitamin B₁₂. Two vitamin B₁₂-dependent enzyme activities (methylmalonyl-CoA mutase, 2.6±0.4 nmol/min/mg protein and methionine synthase, 85.1±38.9 pmol/ min/mg protein) could be found in a cell homogenate of the vitamin B₁₂-supplemented alga. Most of the methylmalonyl-CoA mutase activity and 19.2% of the vitamin B₁₂ accumulated by the algal cells were recovered in the macromolecular fractions with Mᵣ of 150 kDa, although the remaining vitamin B₁₂ was found only in free vitamin B₁₂ fractions.
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