Tertiary folding of the 160-nt P4-P6 domain of the Tetrahymena group I intron RNA involves burying of substantial surface area, providing a model for the folding of other large RNA domains involved in catalysis. Stopped-flow fluorescence was used to monitor the Mg2+-induced tertiary folding of pyrene-labeled P4-P6. At 35 degrees C with [Mg2+] approximately 10 mM, P4-P6 folds on the tens of mill...

Crystalline soybean trypsin inhibitor protein undergoes denaturation on heating which is reversed on cooling. In the range of temperature of 35 to 50 degrees C. a solution of the protein consists of a mixture of native and denatured forms in equilibrium with each other. The equilibrium is only slowly established and its final value at any temperature is the same whether a heated, denatured solu...

We studied the irreversible thermal denaturation of chymopapain, a papain-related cysteine proteinase. It was found that this process follows simple first-order kinetics under all conditions tested. Rate constants determined by monitoring ellipticity changes at 220 or 279 nm are essentially identical, indicating that denaturation involves global unfolding of the protein. Enthalpies (DeltaH(doub...

The Cannizzaro reaction ("RX C") and the benzoin reaction ("RX B") were investigated by density functional theory calculations. Reaction models (benzaldehyde)2 + X(-) + (H2O)n [for X(-) = OH(-) (RX C) n = 8, and for X(-) = CN(-) (RX B) n = 8 or n = 14] were adopted. Three transition states (TSs) were obtained for RX C, and the rate-determining step was confirmed to be the hydride shift. The sin...

For a large class of smooth dagger spaces—rigid spaces with overconvergent structure sheaf—we prove finite dimensionality of de Rham cohomology. This is enough to obtain finiteness of P. Berthelot’s rigid cohomology also in the nonsmooth case. We need a careful study of de Rham cohomology in situations of semistable reduction. Introduction Let R be a complete discrete valuation ring of mixed ch...

If R is a ring with involution, and a† is the Moore-Penrose inverse of a ∈ R, then the element a is called: EP, if aa† = a†a; partial isometry, if a∗ = a†; star-dagger, if a∗a† = a†a∗. In this paper, characterizations of partial isometries, EP elements and star-dagger elements in rings with involution are given. Thus, some well-known results are extended to more general settings.