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Three experimental approaches to identify the residues that are critical for serine specificity of Caenorhabditis elegans mitochondrial EF-Tu2 mutants are presented. All the three approaches reveal that the critical residues essential for the unique serene specificity.

The nucleotide and the corresponding amino acid sequence for the human mitochondrial methionyl-tRNA synthetase (human mtMetRS) are identified and characterized from the human embryonic stem cell (EST) database. Sequence analysis revealed that the human mtMetRS contains the consensus motifs characteristic of a class I aminoacyl-tRNA synthetase but lacks the Zn2+ binding motif and C-terminal dimerization region found in MetRSs from various organisms.

Gel mobility and dna-specific exonuclease resistance analyses were used to investigate the ability of gna trinucleotide loop fragments d(GCGAAAGC) and d(GCGAAGC) in producing stable dna hairpins with Tm values of 76 degrees Celsius. The formed minihairpins exhibited high mobility both on polycramide and 7 M urea combined gel and resistance to T4 dna polymerase activity denoting extraordinary stability. Structure and nature of four fragments, fragments d(GCGNAC) (N=A,G,C, and T), were analyzed using NMR and thermodynamic studies which revealed folded structure believed to be advantageous for minihairpin formation.

The conformational rigidity of 5-methylaminomethyluridine ((mnm)(super 5)U) depends on the 5'-phosphate group. The interactions between the 5-methylaminomethyl and 5'-phosphate groups of (pmnm)(super 5)U limit the conformation about the glycosidic bond to a low anti form. The interaction increases steric repulsion between 2-carbonyl and 2'-hydroxyl groups in the C2'-endo form. The first position of the anticodon of Escherichia coli tRNA(sub 4)(super Arg) for codons AGA/AGG contains (mnm)(super 5)U. A study on conformational analysis uses NMR spectra and molecular dynamics.

Methionine tRNA, which was obtained from bovine liver mitochondria, revealed a new gene sequence-specified nucleoside in the first position of the anticodon. This new anticodon nucleoside exhibited a molecular mass that was 28 Da greater than that of cytidine and an unmodified ribose that was associated with substitution at C5.

Mitochondrial ribosomes of the nematode Ascaris suum are isolated and their physiochemical properties are compared to ribosomes of Escherichia coli. The sedimentation coefficient and buoyant density of Ascaris suum mitochondrial ribosomes are determined.