Chicken muscle ecto-ATPase has unusual enzyme kinetics and properties not found in many other E-type ATPases. To determine whether the unique properties of the chicken ecto-ATPase are inherent in the protein sequence and not mediated by some unique property of the chicken system, we have spliced together two partial cDNAs encoding the ecto-ATPase. The enzymatic properties of the COS (green monkey kidney) cell-expressed protein are indistinguishable from the purified chicken gizzard ecto-ATPase, including a 2- to 3-fold stimulation of membrane-bound activity by crosslinking and lectins, properties not shared by most other E-type ATPases. The expressed enzyme is specific for nucleotide triphosphates (ATPase:ADPase hydrolysis ratio of 26:1) and is inhibited by Cibacron Blue (IC50 = 10 microM). The active, expressed enzyme can be affinity-purified with Cibacron Blue, is relatively resistant to deglycosylation, and is less stable than other E-type ATPases. Expression in the presence of tunicamycin resulted in an inactive, unfolded enzyme.

The variational multiscale (VMS) formulation is used to develop residual-based VMS large eddy simulation (LES) models for Rayleigh-Bénard convection. The resulting model is a mixed model that incorporates the VMS model and an eddy viscosity model. The Wall-Adapting Local Eddy-viscosity (WALE) model is used as the eddy viscosity model in this work. The new LES models were implemented in the finite element code Drekar. Simulations are performed using continuous, piecewise linear finite elements. The simulations ranged from Ra = 10 6 to Ra = 10 14 and were conducted at Pr = 1 and Pr = 7. Two domains were considered: a two-dimensional domain of aspect ratio 2 with a fluid confined between two parallel plates and a three-dimensional cylinder of aspect ratio 1/4. The Nusselt number from the VMS results is compared against three dimensional direct numerical simulations and experiments. In all cases, the VMS results are in good agreement with existing literature.

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