
TY  - JOUR
A1  - Akazawa, T 
A1  - Osmond, CB 
T1  - Structural Properties and Ribulosebisphosphate Carboxylase and Oxygenase Activity of Fraction-1 Protein from the Marine Alga <I>Halimeda cylindracea</I> (Chlorophyta)
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1976
VL  - 3
IS  - 1
SP  - 93
EP  - 103
KW  - 
UR  - https://doi.org/10.1071/PP9760093 
N2  - Ribulosebisphosphate carboxylase/oxygenase activity was detected in Halimeda cylindracea and Chaetomorpha crassa. In H. cylindracea carboxylase activity (72-250 micromoles CO2 fixed per hour per milligram chlorophyll) was sufficient to account for measured photosynthetic rates. The activity of the oxygenase was only 1 % that of the carboxylase but otherwise both enzymes showed properties similar to those of the same enzymes in higher green plants. Fraction-1 protein from H. cylindracea was purified to a homogeneous state as tested by poly- acrylamide gel electrophoresis at pH 8.9. The activity of the ribulose-1,5-bisphosphate carboxylase in the purified preparations was 0.1 micromoles CO2 fixed per minute per milligram protein (pH 7.0). The H. cylindracea fraction-1 protein was shown to comprise two subunits, A and B, with molecular weights 5.4 &#215; 104, and 1.35 x 104, respectively, typical of the plant-type ribulose-1,5-bisphosphate carboxylase. The amino acid composition of the large subunit A was similar to that from spinach and Chlorella enzymes, whereas that of the subunit B was markedly distinguishable from the enzymes of other origins. The close resemblance of the H. cylindricea protein to the plant enzymes was further supported by the formation of a spur in the double immunodiffusion precipitation line, indicating probable existence of sequence-homology of the catalytic larger subunit A, typical of the plant-type enzyme molecules. 
ER  -

