The ribosome-polyuridylic acid-phenylalanyl-soluble ribonucleic acid complex has been shown to be an intermediate in the synthesis of polyphenylalanine. About half of the phenylalanine incorporated into polypeptide from the complex was located in the N-terminus. The formation of this ribosomal complex with phenylalanyl-soluble ribonucleic acid is rate-limiting in the synthesis of polyphenylalan...

A short treatment with ethylenedinitrilotetraacetic acid to permeabilize bacteria for various antibiotics or treatment with the ribonucleic acid (RNA) synthesis inhibitor rifampin causes a slow degradation of 50S and 30S ribosomal particles and of the corresponding 23S and 16S ribosomal RNA species (about 25 percent in 1 h). The effects are additive such that the decay is about 50 percent/h if ...

Aphidicolin, a known inhibitor of eucaryotic deoxyribonucleic acid (DNA) polymerase alpha, efficiently inhibited amplification of ribosomal DNA during oogenesis in Xenopus laevis. DNA polymerase alpha, but not DNA polymerase gamma, as isolated from ovaries, was sensitive to aphidicolin. DNA polymerase beta was not detectable in Xenopus ovary extracts. Therefore, DNA polymerase alpha plays a maj...

Ribonucleic acid isolated from cerebral cortex of mature male and female rats was fractionated by chromatography on methylated albumin Kieselguhr columns or by sucrose gradient centrifugation. Three principal fractions were obtained with analytical ultracentrifuge s~o,~ values of 4, 17, and 28. By comparison with ribonucleic acid prepared from purified rat brain ribosomes, the 17 S and 28 S fra...

Active 30S and 50S ribosomal subunits were isolated from Bacillus subtilis. These subunits were able to perform not only protein synthesis in the presence of artificial or natural messenger ribonucleic acid but also the specific functions characteristic of each of the subunits. Thus the 30S subunits alone are able to bind formyl-methionyl-transfer ribonucleic acid, and the 50S subunits carry th...