The presence of medium Pi (half-maximal concentration of 20 microM at pH 8.0) was found to be required for the prevention of the rapid decline in the rate of proton-motive force (pmf)-induced ATP hydrolysis by Fo.F1 ATP synthase in coupled vesicles derived from Paracoccus denitrificans. The initial rate of the reaction was independent of Pi. The apparent affinity of Pi for its "ATPase-protectin...

Bioprocessing strategies to improve production of the heterologous protein parathion hydrolase from recombinant Streptomyces lividans were investigated. Initial limitations to increased production were overcome by using large amounts of nutrients and feeding these nutrients throughout the fermentation. Batch addition of such large amounts of nutrients resulted in byproduct acid accumulation. Ou...

Activation of ribulose1,5-bisphosphate carboxylase by CO, and Mgz+ is slow and reversible. At subsaturating concentrations of CO, and Mg2+, positive effectors increase and negative effectors decrease the amount of active enzyme at equilibrium. Preequilibrium experiments indicated that both positive and negative effectors inhibit the rates of enzyme activation and deactivation. Greater than 99% ...

Primary monolayer cultures of human umbilical vein endothelium produce prostacyclin (PGI2) in response to stimulation by thrombin, ionophore A23187, arachidonic acid, and the prostaglandin endoperoxide, PGH2. None of these treatments had a significant effect on the capacity of the endothelium to produce PGI2 in response to subsequent stimulation by PGH2. By contrast, endothelium initially expos...

The alpha-toxin-permeabilized betaTC3 cell has been utilized as an experimental model for the identification of protein phosphatases responsible for the dephosphorylation and deactivation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) in situ. In this model, the elevation of Ca2+ from 0.05 to 10 microM induced the near-total conversion of CaM kinase II into a Ca2+/calmodulin-ind...