Ribonucleic acids base composition

BSA was effective for the derivatization of purine and pyrimidine bases [456] and nucleosides [457]. Bases were silylated by heating at 150°C with BSA—acetonitrile (1 3) for 45 min. It was stated that under these conditions the TMS derivative of guanine can be prepared reproducibly, but both cytosine and 5-methylcytosine provided two peaks. Silylation of nucleosides, including pseudouridine, was carried out by heating at 120°C with a 100-fold excess of BSA for 2 h. With the use of OV-17 as the stationary phase, this procedure was adopted for the determination of the composition of ribonucleic acids. 

RNA (ribonucleic acid) A nucleic acid found mainly in the cytoplasm and involved in protein synthesis. It is a single polynucleotide chain similar in composition to a single strand of DNA except that the sugar ribose replaces deoxyribose and the pyrimidine base uracil replaces... 

Bacterial and mammalian ribosomes have many similarities. However, the mammalian ribosomes (80 S, mol wt 3.5-5 x 10 ) are a little larger than the bacterial ribosomes, and the latter dissociate more easily than the mammalian ribosomes. (After dissociation of liver ribosome, 4 particles differing in size can be obtained 32 S, 47 S, 50 S, and 56 S. It is believed that 50 S is a dimer of the 32 S subparticle, whereas 56 S is a 47 S particle that includes the nascent protein.) The ribosome is composed of protein and a considerable amount of ribonucleic acid. In bacteria, about 80% of the cell s total ribonucleic acid is in the ribosomes. The base compositions of ribosomal RNA obtained from various sources are, in general, remarkably similar. But this base composition differs from the base composition of soluble RNA inasmuch as it does contain a smaller amount of the rare bases found in soluble RNA. The base composition of ribosomal RNA also differs from that of messenger RNA3. 

There are several distinct types of ribonucleic acid, which are defined in terms of molecular size, base composition and functional properties. They differ from DNA in... 

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