Arginine deiminase from the extreme halophilic archaebacterium Halobacterium salinarium was purified to homogeneity in a four-step procedure with a 310-fold enrichment. The enzyme consists of two identical subunits of 55 kDa; its native molecular mass is 105 kDa. The pI of 4.7 indicates that acidic nature of the protein, which is evidenced by its amino acid composition, which shows an excess of more than 15% of acidic amino acids. The N-terminal amino acid of the enzyme is lysine. Arginine deiminase from Halobacterium salinarium exhibits its highest catalytic activity in the presence of 3.5 M-NaCl, pH 7.6, and at 40 degrees C. The half-activity constant, Ks, for arginine is 3.1 mM. The enzyme is inhibited by ornithine.

No abstract

The tasks and aims of the Bochum Observatory are popularization of astronomy and space sciences, and adult education. In general, as a cultural center for natural sciences we must translate scientific nomenclature into the language of the nonspecialist. Astronomy is ideal for presenting the basic facts of scientific methodology and reasoning to the publicA planetarium is the most versatile instrument for teaching basic astronomy and space sciences to the general public as well as to school groups. We take great care to avoid a lecture-like style in the programs. Audience surveys have shown that most visitors don’t want to get the feeling of being educated as in school. Nevertheless, we first have to motivate before we can educate. Instead, most visitors want merely to enjoy astronomy in the pleasant atmosphere of the dome. Consequently, our public planetarium shows contain elements of entertainment. We use many special effects, panoramas, and all-sky projections for a most precise simulation of astronomical phenomena. The audience should get the thrilling impression of witnessing things from close up. For example, they all become passengers on an imaginary spacecraft visiting the rugged terrain of Valles Marineris on Mars, the swirling clouds in Jupiter’s atmosphere, or even the vicinity of a whirlpool-like accretion disc around a supermassive black hole in the core of an active galaxy. We use the potential of the planetarium as an “illusion factory” to increase the visitors’ positive attitude towards astronomy and space travel. Special music, sound, and noise effects add to the impression.