Comparison of x-ray crystal structures of an acyl-enzyme intermediate of subtilisin Carlsberg formed in anhydrous acetonitrile and in water

The x-ray crystal structures of trans-cinnamoyl–subtilisin, an acyl-enzyme covalent intermediate of the serine protease subtilisin Carlsberg, have been determined to 2.2-Å resolution in anhydrous acetonitrile and in water. The cinnamoyl–subtilisin structures are virtually identical in the two solvents. In addition, their enzyme portions are nearly indistinguishable from previously determined structures of the free enzyme in acetonitrile and in water; thus, acylation in either aqueous or nonaqueous solvent causes no appreciable conformational changes. However, the locations of bound solvent molecules in the active site of the acyl- and free enzyme forms in acetonitrile and in water are distinct. Such differences in the active site solvation may contribute to the observed variations in enzymatic activities. On prolonged exposure to organic solvent or removal of interstitial solvent from the crystal lattice, the channels within enzyme crystals are shown to collapse, leading to a drop in the number of active sites accessible to the substrate. The mechanistic and preparative implications of our findings for enzymatic catalysis in organic solvents are discussed.

Study of the effects of fluoride on teeth of children in Cleveland Public Schools /

Mode of access: Internet.

The alkali fluoride and carbonate bead test for uranium /

"April 1956."

Vapor pressures of the sodium fluoride-zirconium fluoride system and derived information /

See errate for page 1 at end of item.

The preparation of uranium hexafluoride from uranium ores and concentrates by fluoride volatility processes : an annotated bibliography /

"Feed Materials Production Center, National Lead Company of Ohio"--Cover.

The recovery of magnesium and HF from magnesium fluoride : a literature search /

"Feed Materials Production Center, National Lead Company of Ohio"--Cover.

Ammonium diuranate precipitation with anhydrous ammonia /

Ammonium diuranate has been precipitated from nitric acid solutions by the addition of anhydrous ammonia on both laboratory and production scales. This process produced more dense and more rapidly filtered precipitates than those formed by the addition of aqueous ammonia or slurried calcium hydroxide. The filtrates from the anhydrous ammonia process were lower in uranium content than those obtained by the addition of the other reagents. Processing equipment and precipitate characteristics are discussed.

Fluoride in Illinois : sources, environmental and health effects, and a proposed ambient standard /

Bibliograhy: p. 71-84.

Rules and regulations relating to the handling of anhydrous ammonia and low pressure nitrogen solutions, equipment containers and storage facilities /

Cover title.

Risk assessment of exposure to radium and fluoride in Illinois public water supplies /

Prepared for Illinois Dept. of Energy and Natural Resources, Energy and Environmental Affairs Division.

Zur kenntnis der fluoride.

Thesis (doctoral)--