Escherichia coli can grow aerobically in defined media containing inorganic salts and any one of a wide range of carbon compounds. Whatever the nature of the carbon source. it is fed into the amphibolic pathways [glycolysis, pentose phosphate pathway, Krebs (tricarboxylic acid) cyclel, from which stem all the biosynthetic pathways required for making the components of new cell material. The ope...

The mechanosensitive channel of small conductance (MscS) is a bacterial tension-driven osmolyte release valve with homologues in many walled eukaryotic organisms. When stimulated by steps of tension in excised patches, Escherichia coli MscS exhibits transient opening followed by reversible adaptation and then complete inactivation. Here, we study properties of the inactivation transition, which...

Vanillyl-alcohol oxidase (EC 1.1.3.7) from Penicillium simplicissimum was modified with p-mercuribenzoate. One cysteine residue reacts rapidly without loss of enzyme activity. Three sulfhydryl groups then react in an 'all or none process' involving enzyme inactivation and dissociation of the octamer into dimers. The inactivation reaction is slowed down in the presence of the competitive inhibit...

Arginine kinase plays an important role in the cellular energy metabolism of invertebrates. Dimeric arginine kinase (dAK) is unique in some marine invertebrates. The effects of Zn²(+) on the unfolding and aggregation of dAK from the sea cucumber Stichopus japonicus were investigated. Our results indicated that Zn²(+) caused dAK inactivation accompanied by conformational unfolding, the exposure ...

Acetyl-CoA carboxylase (ACC) plays a critical role in the regulation of fatty acid metabolism and its two isoforms, ACCalpha and ACCbeta, appear to have distinct functions in the control of fatty acid synthesis and fatty acid oxidation, respectively. They are regulated by similar short-term mechanisms of allosteric activation by citrate, and reversible phosphorylation and inactivation, and ther...

NAD+ glycohydrolase (NADase; EC 3.2.2.5) is an enzyme that catalyses hydrolysis of NAD+ to produce ADP-ribose and nicotinamide. Its physiological role and the regulation of its enzymic activity have not been fully elucidated. In the present study, the mechanism of self-inactivation of NADase by its substrate, NAD+, was investigated by using intact rabbit erythrocytes and purified NADase. Our re...

The effects of pressure, temperature, and pH on the n&\-i@ of purified rabbit skeletal muscle magnesium-activated ATPnsc were measured. The enzyme is rnpidl> and irreversibly inactivated by both temperature and pressure and shows no rvidencc of reversible denaturation. The extent of irreversible inactivation depends on the amount of pressure applied and is largest at the optimum pH of the enzyme.

Lesion studies have suggested that the auditory cortex may not be involved in many aspects of hearing. A recent report casts doubt on this long-held view by showing that reversible inactivation of the auditory cortex leads to a transient impairment in tone detection and frequency discrimination.

Purified chicken intestinal alkaline phosphatase is active at pH 8 to 9, but becomes rapidly inactivated with change of pH to 6 or less. Also, a solution of the inactivated enzyme at pH 4.5 rapidly regains its activity at pH 8. In the range of pH 6 to 8 a solution of purified alkaline phosphatase consists of a mixture of active and inactive enzyme in equilibrium with each other. The rate of ina...