Solid phase synthesis of the 5''-half of the initiator t-RNA from B. subtilis.

Using cyanoethyldiisopropylamino phosphoramidite chemistry, four oligonucleotides constituting a part of the sequence of the initiator t-RNA from B. subtilis were synthesized. For the protection of the exocyclic amino functions of bases, phenoxyacetyl group was used for adenine and guanine, and acetyl group was preferred for cytosine. With these labile groups, final deprotection of the oligonucleotides can be performed in milder conditions, allowing the incorporation of 5,6-dihydrouridine in a 35-mer constituting the 5'-end of the t-RNA.     

Structural changes in t-RNA from changes in the Raman scattering intensities

Laser Raman spectra of a mixture of yeast t-RNA's are examined as a function of temperature and after total alkaline hydrolysis to mononucleotides; the data are interpreted on the basis of extensive preliminary studies previously reported from this laboratory on the Raman spectral properties of numerous synthetic model compounds. Since the Raman intensities observed are extremely sensitive to conformational changes in the nucleic acid, much useful structural information can be obtained.     

Presence of the Different Sequence in the Terminal Region of Glycine-Specific t-RNA

Milk β₂A-globulin was isolated by rechromatography of the globulin fraction of human milk on DEAE-cellulose column. Milk β₂A-globulin containinig 12.1% of carbohydrates was homogeneous in the electrophoresis and ultracentrifuge. Physicochemical properties of human milk β₂A-globulin were studied.     

Effects of cis-Platin on t-RNA of Saccharomyces cerevisiae

We synthesized three hydantocidin derivatives and evaluated their herbicidal activity in order to elucidate the role of the spirohydantoin system at the anomeric center of hydantocidin. With application to foliage at 1000 ppm, only α-ureidoamide 14 demonstrated activity, the remaining compounds being found to be inactive.     

The fractionation of t-RNA on N,N'-bis(3-aminopropyl)-piperazine substituted-Sepharose

An anion exchange agarose has been prepared by modifying sepharose 6B with N,N′-bis (-3-aminopropyl) piperazine. This material (BAPP-Sepharose) has been used for the fractionation of t-RNA from E.coli by column chromatography. The results obtained with gram quantities of crude t-RNA at pH 4.6 and pH 8.0 as measured by the elution patterns of alanyl, arginyl, aspartyl, leucyl, lysyl, methionyl, phenylalanyl, prolyl, seryl, tyrosyl, and valyl t-RNA are described.     

A common mitochondrial DNA mutation in the t-RNA(Lys) of patients with myoclonus epilepsy associated with ragged-red fibers

Nucleotide sequence analyses of muscle mitochondrial DNA (mtDNA) from a patient with myoclonus epilepsy associated with ragged-red fibers (MERRF) revealed 33 single base substitutions, including 23 in coding regions for mitochondrial polypeptides and 10 in non-coding regions, as compared with the normal human mtDNA sequence. Three substitutions, in COI, ND4, and Cytb, would result in amino acid substitutions, which are conserved among species. Of three patients with MERRF, all had an identical A to G base substitution only at nucleotide position 8344 in the t-RNA(Lys) region. The substitution was not found in 15 controls. Various degrees of the combined enzymic defects in the oxidative phosphorylation system of mitochondria were found in the MERRF patients. The defects could be explained by altered function or processing of the mutant t-RNA(Lys). This mutation in the t-RNA(Lys) is the most probable cause of MERRF.     

Mitochondrial phenylalanyl t-RNA synthetase from yeast: formation of enzyme-substrate complexes shown by heat or SH reagent inactivation

The binding of substrates to purified mitochondrial phenylalanyl-tRNA synthetase from yeast was examined using the kinetics of heat or p-hydroxymercurybenzoate inactivation. Individually magnesium chloride and each of the substrates protect the enzyme against thermal denaturation and p-hydroxymercurybenzoate inhibition. No enzyme protection is observed with ATP alone against p-hydroxymercurybenzoate inhibition. The combinations of the various substrates induce a synergistic protection effect. Protection constants of 31 microM and 0.3 microM were found for L-Phe and mt tRNAPhe respectively, from heat inactivation studies. The inhibition of the enzyme activity by p-hydroxymercurybenzoate can be reverted by 2-mercaptoethanol or dithiothreitol.