Some chemical components of mitochondria and microsomes from germinating castor beans

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Abstract
Castor-bean mitochondria and microsomes prepared by differential centrifuging of homogenates in sucrose-phosphate were analyzed for ribonucleic acid (RNA), acid-soluble phosphate, phospholipid and protein. Expressed on a protein basis the mitochondria have relatively low phospholipid and RNA contents, whereas the acid-soluble phosphate is higher than that of the microsomes. These facts, and particularly the very high RNA content of the microsomes, point to a general similarity to corresponding particles of animal origin. During the first 4 days of germination there is an increase in mitochondrial protein and this is accompanied by an increase in all the other components. After the 5th day these components decrease, especially the acid-soluble phosphate. The proportion of RNA and phospholipid to protein nitrogen remains more or less constant throughout, but that for acid-soluble phosphate declines. A similar decline in acid-soluble phosphate is noted in the microsomes; in these particles there is no increase in protein or other components in the first few days of germination. The water content of the mitochondria was determined and its variation in response to media of different tonicity measured.
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