Photosynthetic Carbon Metabolism of Isolated Corn Chloroplasts

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Abstract
Chloroplasts have been isolated from 4- to 6-day-old corn (Zea mays) leaves capable of assimilating 45 micromoles CO2 per milligram chlorophyll per hour. The effects of various factors such as inorganic phosphate, reducing agents, inhibitors, intermediates of the photosynthetic carbon reduction cycle, organic acids, and oxygen on the photosynthetic rate and on the distribution of 14C within the products by these chloroplasts were determined. The photosynthetic carbon metabolism of the corn plastids appeared to be similar to that already observed in spinach and pea chloroplasts. It was concluded that the corn plastids can fix CO2 at meaningful rates via the photosynthetic carbon reduction cycle of Calvin without the operation of a cycle involving the C-4 compounds, malate and aspartate.