Glucose 6-phosphate dehydrogenase (EC 1.1.1.49) has been partially purified from Anacystis nidulans and Anabaena flos-aquae by means of ammonium sulfate fractionation and exclusion gel chromatography and the kinetic properties determined.Glucose 6-phosphate dehydrogenase from these blue-green algae exhibits Michaelis-Menten kinetics at pH 6.7. At this pH, Km values of 0.37 mm for glucose 6-phos...

The energy-dependent uptake of calcium by inverted membrane vesicles of Escherichia coli was investigated. Methods for preparation and storage of the vesicles were devised to allow for the maximal activity and stability of the calcium transport system. The pH and temperature optima for the reaction were observed to occur at pH 8.0 and 30”, respectively. The effects of various ions on the transp...

The possible role of phosphate in the calcium translocation process in human erythrocyte inside-out vesicles (IOV) has been investigated. Millimolar phosphate was found to stimulate the initial velocity of calcium transport 3to 4-fold and increase the K , (Ca”’) of calcium transport 2to 3-fold. The stimulation of cdcium transport by phosphate was due to an active, calcium-dependent, calmodulin-...

The energy-dependent uptake of calcium by inverted membrane vesicles of Escherichia coli was investigated. Methods for preparation and storage of the vesicles were devised to allow for the maximal activity and stability of the calcium transport system. The pH and temperature optima for the reaction were observed to occur at pH 8.0 AND 30 DEGREES, RESPECTIVELY. The eft was found that the extent ...

In the small intestine, 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] stimulates both calcium (Ca) and inorganic phosphate (Pi) absorption. This is mediated through an increase in mucosal-to-serosal flux (Jms) whereas the serosal-to-mucosal flux (Jsm) remains unchanged. We now report that in rat proximal colon, 1,25(OH)(2)D(3) produces active Ca absorption without affecting Pi transport, and tha...

Transport of inorganic phosphate (P(i)) is mediated by proteins belonging to two solute carrier families (SLC20 and SLC34). Members of both families transport P(i) using the electrochemical gradient for Na(+). The role of the SLC34 members as essential players in mammalian P(i) homeostasis is well established, whereas that of SLC20 proteins is less well defined. The SLC34 family comprises the f...

1. The properties and kinetics of the 2,3-diphosphoglycerate-dependent phosphoglycerate mutases are discussed. There are at least three possible mechanisms for the reaction: (i) a phosphoenzyme (Ping Pong) mechanism; (ii) an intermolecular transfer of phosphate from 2,3-diphosphoglycerate to the substrates (sequential mechanism); (iii) an intramolecular transfer of phosphate. It is concluded th...

Despite the importance of extracellular phosphate in many essential biological processes, the mechanisms of phosphate transport across the epithelium of different intestinal segments remain unclear. We have used an in vitro method to investigate phosphate transport at the brush border membrane (BBM) of intact intestinal segments and an in vivo method to study transepithelial phosphate absorptio...