Characteristics of ribosomes isolated from roots of Zea mays

• Published in: Biochimica et biophysica acta Vol. 91; no. 4; pp. 598 - 605
• Main Author: Hsiao, Theodore C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16.12.1964
• Subjects: Biochemical Phenomena; Biochemistry; Chromatography; Edible Grain; Escherichia coli; Magnesium; OldMedline; Plants; Ribosomes; RNA; Ultracentrifugation; Zea mays; MAGNESIUM; ESCHERICHIA COLI; RNA; GRAIN; BIOCHEMISTRY; CORN; EXPERIMENTAL LAB STUDY; PLANTS; RIBOSOMES; CHROMATOGRAPHY; ULTRACENTRIFUGATION
• ISSN: 0926-6550; 0006-3002; 1878-2256
• DOI: 10.1016/0926-6550(64)90007-6

Ribosomes were isolated from root tips of corn ( Zea mays) and their properties studied. Five ribosomal components (40 S, 60 S, 80 S, 120 S, and 150 S), with the 80-S component predominating, were present in the cytoplasmic extract. Sedimentation coefficients at infinite dilution were determined for all except the 150-S component. Purified ribosomes contained 43% RNA which was characterized by a high guanine and relatively high cytosine content. The 80-S component dissociated into 60-S and 40-S particles when pH of the medium was increased from 6.5 to 8.0 or higher. Magnesium (0.5–2 mM) prevented the dissociation. In marked contrast to the 70-S ribosome of Escherichia coli, the 80-S ribosome of corn did not require added magnesium to maintain its integrity in a solution of nearly neutral pH and low ionic strength. In fact, 5 mM magnesium in such a solution caused the association of corn ribosomes into large random aggregates. Ribosomes of different organisms differ in the level of magnesium required to preserve their 70–80-S component and may be divided accordingly into three broad groups exemplified by E. coli, yeast, and corn ribosomes.