Mutational analysis of residues in the nucleotide binding domain of human terminal deoxynucleotidyl transferase

Human terminal deoxynucleotidyl transferase (TdT) was overexpressed in a baculovirus system. The pure recombinant enzyme was identical in size, activity, kinetic constants, and metal effects to native enzyme. Three amino acids, within either the putative nucleotide binding domain and part of a DNA polymerase consen sus sequence, YGDTDSLF, or a TdT consensus sequence, GGFRRGK, were altered by site-directed mutagenesis. The four mutant forms of terminal transferase were also overexpressed in the baculovirus expression system and purified from Trichoplusia ni larvae by a monoclonal antibody affinity column and compared with wild-type enzyme with respect to thermostabilities, secondary structure, metal effects, and kinetic parameters

Mutational analysis of active site residues of human adenosine deaminase

Adenosine deaminase was overexpressed in a baculovirus system. The pure recombinant and native enzymes were identical in size, Zn2+ content, and activity. Five amino acids, in proximity to the active site, were replaced by mutagenesis. The altered enzymes were purified to homogeneity and compared to wild-type adenosine deaminase with respect to zinc content, enzymatic activity, and kinetic parameters. All but one of the alterations produced significant activity perturbations. Replacement of Cys262 produced a protein that retained at least 30-40% of wild-type activity. In contrast, replacements of His17, His214, His238, and Glu217 resulted in dramatic losses of enzyme activity. None of these mutants exhibited large variations in Km. The proteins produced from alterations of amino acids implicated in metal coordination were slightly activated by inclusion of Zn2+ throughout purification. These experiments confirm that in the active enzyme Zn2+ plays a critical role in catalysis, that a histidine or glutamate residue plays a mechanistic role in the hydrolytic deamination step, and that cysteine is not involved in the catalytic mechanism of adenosine deaminase. These data support the roles for these amino acid residues suggested from the x-ray structure of murine adenosine deaminase (Wilson, D. K., Rudolf, F. B., and Quicho, F. A. (1991) Science 252, 1278-1284)

Vocal Culture in the Age of Laryngoscopy

For several months beginning in 1884, readers of Life, Science, Health, the Atlantic Monthly and similar magazines would have encountered half-page advertisements for a newly patented medical device called the ‘ammoniaphone’ (Figure 2.1). Invented and promoted by a Scottish doctor named Carter Moffat and endorsed by the soprano Adelina Patti, British Prime Minister William Gladstone and the Princess of Wales, the ammoniaphone promised a miraculous transformation in the voices of its users. It was recommended for ‘vocalists, clergymen, public speakers, parliamentary men, readers, reciters, lecturers, leaders of psalmody, schoolmasters, amateurs, church choirs, barristers, and all persons who have to use their voices professionally, or who desire to greatly improve their speaking or singing tones’. Some estimates indicated that Moffat sold upwards of 30,000 units, yet the ammoniaphone was a flash in the pan as far as such things go, fading from public view after 1886

Opera and Hypnosis: Victor Maurel’s Experiments with Verdi’s Otello

One day in his private home on the avenue Bugeaud, in Paris’s sixteenth arrondissement, the famous baritone Victor Maurel hosted a meeting which combined music with hypnotism of a young woman

Science, Technology and Love in Late Eighteenth-Century Opera

It is a tale told by countless operas: young love, thwarted by an old man’s financially motivated marriage plans, triumphs in the end thanks to a deception that tricks the old man into blessing the young lovers’ union. Always a doddering fool, the old man is often also an enthusiast for knowledge. Such is the case, for instance, in Carlo Goldoni’s comic opera libretto Il mondo della luna (1750), in which Buonafede’s interest in the moon opens him to an elaborate hoax that has him believe he and his daughters have left Earth for the lunar world; and also in the Singspiel Die Luftbälle, oder der Liebhaber à la Montgolfier (1788), wherein the apothecary Wurm trades Sophie, the ward he intended to marry himself, for a technological innovation that will make him a pioneering aeronaut

Unsound Seeds

With this image of a curtain hiding and at the same time heightening some terrible secret, Max Kalbeck began his review of the first Viennese performance of Richard Strauss’s Salome. Theodor W. Adorno picked up the image of the curtain in the context of Strauss’s fabled skill at composing non-musical events, when he identified the opening flourish of Strauss’s Salome as the swooshing sound of the rising curtain. If this is so, the succès de scandale of the opera was achieved, in more than one sense, as soon as the curtain rose at Dresden’s Semperoper on 10 December 1905. Critics of the premiere noted that the opera set ‘boundless wildness and degeneration to music’; it brought ‘high decadence’ onto the operatic stage; a ‘composition of hysteria’, reflecting the ‘disease of our time’, Salome is ‘hardly music any more’.The outrage did not end there