Comparison of porcine liver tRNA preparations: purification of tRNA and its separation from RNA-peptidyl complexes

Porcine thyroid cytosolic, latent, alkaline, ribonuclease: does an acidification step during purification alter the enzyme's properties?

The effect of an acidic step in the purification of porcine thyroid, latent, alkaline ribonuclease was studied using highly purified acid-treated and non-acid-treated enzymes. The enzymes differed by affinity and CM-cellulose chromatography, specific activity, in distribution among multiple forms, in response to some mono- and divalent salts, in degree of inhibition by p-chloromercuriphenylsulfonate and ribonuclease inhibitor, in activity toward poly (U). The acid-treated enzyme was very heterogeneous as shown by chromatography on affinity and ion-exchange columns and electrophoresis. The enzymes had similar molecular weights, pH optima, ionic strength effects, general specificity and products.

A procedure for the rapid preparation of 14C-aminoacyl-transfer RNA and its use in the assay of class I ribonucleases and ribonuclease inhibitor

The presence of ribonuclease inhibitor and/or the activity of class I ribonucleases can conveniently be measured, at all stages of purification, by a highly sensitive assay based on the loss of radioactivity during the concomitant hydrolysis of tRNA and small amounts of 14C-labeled aminoacyl-tRNA. The rapid, economical assay, which is readily adaptable to homologous tRNA substrates, eliminates the necessity of filtration, centrifugation and ultraviolet spectroscopy measurements required by most other assays and is particularly suitable for multiple samples and kinetic measurements.

Preparation of oligonucleotides and their use in molecular weight estimations

Yeast RNA was used to prepare oligonucleotides employed to calibrate a G-50 Sephadex column. The oligonucleotides' preparation, isolation, desalting and characterization is described. Data obtained by chromatography of the oligonucleotides demonstrate that the molecular weights of oligonoucleotides can be easily determined by interpolation using plots of elution volumes (Ve) versus molecular weights (M). Errors greater than 20% are obtained if the conventional plot of Ve-Vo/Vs versus log M is used (where Vo is the void volume of the column and Vs is the volume of the column occupied by the inert phase, the G-50 Sephadex).