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G Keith

Publications and source records attributed to G Keith.

At least 127 records · Page 7Linked to original sources
PubMed1978

Methylation of yeast tRNAPhe by enzymes from cytoplasm, chloroplasts and mitochondria of Phaseolus vulgaris.

Pure yeast tRNAPhe was used as a substrate to compare the tRNA methylating activities in Phaseolus vulgaris cytoplasm, chloroplasts and mitochondria, in the presence of S-adenosyl[Me-3H]methionine. The resulting [Me-3H]-tRNAPhe was then analyzed, using the techniques of nucleotide sequence determination. Cytoplasmic and mitochondrial enzymes catalyze the methylation (into m5C) of C48 present in the extra-loop, while chloroplast enzyme preparations catalyze the modification (into m1A) of A14 present in the dihydrouridine loop of tRNAPhe.

Base Sequence↗
PubMed1978

Primary structure of bovine liver tRNATrp.

Purified tRNATrp from bovine liver, accepting 1700 pmol tryptophan per A260nm unit, was completely digested with pancreatic ribonuclease and T1 ribonuclease. The sequences of the resulting oligonucleotides were determined and the primary structure of the tRNA was deduced. These analyses showed numerous incomplete post-transcriptional modifications, and several positions heterogenously occupied by two different nucleotides, which lead us to think that in bovine liver there exist a mixture of several tRNATrp.

Animals↗
PubMed1978

[Nucleotide sequence determination of yeast mitochondrial phenylalanine-tRNA].

The primary structure of mitochondrial tRNAPhe from Saccharomyces cerevisiae, purified by two-dimensional polyacrylamide gel electrophoresis, was determined using, standard procedures on in vivo 32P-labeled tRNA, as well as the new 5'-end postlabeling techniques. We propose a cloverleaf model which allows for tertiary interaction between cytosine in position 46 and guanine in position 15 and maximizes base pairing in the psi C stem, thus excluding the uracile in position 50 from base pairing in the psi C stem. Comparison of the primary structure of this tRNA with all other known procaryotic, chloroplastic or cytoplasmic tRNAsPhe sequences does not lead to any conclusion about the endosymbiotic theory of mitochondria evolution.

Base Sequence↗
PubMed1978

The primary structure of rabbit, calf and bovine liver tRNAPhe.

Highly purified tRNAPhe from rabbit liver, calf liver and bovine liver were completely digested with pancreatic ribonuclease and ribonuclease T1. The oligonucleotides were separated and identified. The tRNAPhe from rabbit liver and calf liver were partially cleaved with ribonuclease T1 or by action of lead acetate. We describe the analyses of the large fragments and the derivation of the primary structure of these mammalian tRNAsPhe.

Animals↗
PubMed1978

Nucleotide sequence at the 5' extremity of turnip yellow mosaic virus genome RNA.

The sequence of the first 110 nucleotides at the 5' extremity of turnip yellow mosaic virus genome RNA has been determined. The sequence is blocked at its 5' terminus with the group pppm(7)G and contains two AUG triplets. The determined sequence bears a strong resemblance to the 5' noncoding region of rabbit beta-globin mRNA. Region 95-103 of the sequence can base-pair with part of the 3' extremity of either the genome RNA or the coat protein mRNA.

Journal Article↗
PubMed1978

Primary structure of yeast mitochondrial DNA-coded phenylalanine-tRNA.

Mitochondrial tRNAPhe from Saccharomyces cerevisiae isolated by two-dimensional gel electrophoresis was sequenced by fingerprinting uniformly labeled 32 P-tRNA as well as by 5'-end postlabeling techniques. Its sequence was found to be: pG-C-U-U-U-U-A-U-A-G-C-U-U-A-G-D-G-G-D-A-A-A-G-C-m22G-A-U-A-A-A-phi-U-G-A-A-m1G-A-phi-U-U-A-U-U-U-A-C-A-U-G-U-A-G-U-phi-C-G-A-U-U-C-U-C-A-U-U-A-A-G-G-G-C-A-C-C-A. The secondary structure we propose, in order to maximize base pairing in the phiC stem and to allow tertiary interaction between G15 and C46, excludes U50 from base pairing giving a bulge in the phiC stem. No conclusion can be drawn concerning the endosymbiotic theory of mitochondria evolution by comparing the primary structure of mt. tRNAPhe with other sequenced tRNAsPhe. This mt.tRNAPhe lacks some of the structural elements reported to be involved in the yeast cytoplasmic phenylalanyl-tRNA ligase recognition site and cannot be aminoacylated by purified yeast cytoplasmic phenylalanyl-tRNA ligase.

Base Sequence↗
PubMed1977

Chemical basis for brain-specific serine transfer RNAs.

Serine tRNA from rat brain can be resolved into six isoaccepting species. Three of these species show the same chromatographic behavior as the seryl tRNAs from other rat organs, whereas the remaining species appear to be specific for brain. The isoacceptor tRNAs were purified to homogeneity by chromatography on benzoylated DEAE-cellulose followed by reversed-phase chromatography. We found that the additional species of serine tRNA in brain differ from their counterparts derived from other rat organs by a lack of a specific guanosine ribose-methylation in the dihydrouridine loop. In addition, when total liver tRNA was compared with total brain tRNA, the same degree of undermethylation with respect to 2'-O-methylguanosine was found as a general phenomenon.

Animals↗
PubMed1977

Aminoacylation of tRNA Trp from beef liver, yeast and E. coli by beef pancrease tryptophan-tRNA ligase. Stoichiometry of tRNATrp binding.

The Michaelis constants and the maximum velocities in the aminoacylation reaction of tRNATrp from beef liver, yeast and E. coli by pure beef pancreas tryptophan-tRNA ligase show that this mammalian enzyme recognizes and charges the two eucaryotic tRNAs with the same efficiency. The rate of aminoacylation of the procaryotic tRNATrp by the enzyme is three orders of magnitude lower. The pH optimum of aminoacylation is 8 for both eucaryotic tRNAs. The optimum magnesium concentration is different. The rate is maximum when magnesium concentration is stoichiometric to ATP concentration for tRNATrp from beef liver and 10 mM above ATP concentration for tRNATrp from yeast. The number of binding sites on the enzyme for the two eucaryotic tRNAs has been measured by equilibrium filtration on Sephadex G-100 and found equal to two.

Adenosine Triphosphate↗
PubMed1977

The nucleotide sequence of phenylalanine tRNA from Bacillus subtilis.

The nucleotide sequence of tRNA(Phe) from Bacillussubtilis W 23 has been determined using (32)P labeled tRNA. This is the second B. subtilis tRNA so far reported. The nucleotide sequence was found to be pG-G-C-U-C-G-G-U-A-G-C-U-C-A-G-U-D-G-G-D-A-G-A-G-C-A-A-C-G-G-A-C-U-Gm-A-A- ms(2)i(6)A-A-psi-C-C-G-U-G-U-m(7)G-U-C-G-G-C-G-G-T-psi- C-G-A-U-U-C-C-G-U-C-C-C-G-A-G-C-C-A-C-C-A(OH).Images

Bacillus subtilis↗