The loss of activity due to proteolysis of purified L-asparaginase and beta-galactosidase from different sources correlates with the thermal instability of the enzymes. A similar correlation is found when populations of soluble proteins from micro-organisms grown at different temperatures are compared for proteolytic susceptibility and thermal stability. It is proposed that there is a general c...

A liquid, colorimetric presence-absence coliphage detection method based on the induction of beta-galactosidase by Escherichia coli is described. The release of beta-galactosidase in the medium due to lytic cell infections by coliphages permits the hydrolysis of a yellow chromogenic substrate that develops into a distinct red coliphage positive sample, while a coliphage negative sample remains ...

Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expression of beta-galactosidase was regulated by lysine (and arginine), as previously described for aspartokinase III.

Relaxed (relA) mutants of Escherichia coli are defective in beta-galactosidase synthesis during amino acid limitation. We show here that this defect comprises both a transcriptional component and a translational component.

Pressure-damaged Escherichia coli O157 cells were more acid sensitive than native cells and were impaired in pH homeostasis. However differences in acid sensitivity were not related to differences in cytoplasmic pH (pH(i)). Cellular beta-galactosidase was more acid labile in damaged cells. Sensitization to acid may thus involve loss of protective or repair functions.

Here we show that the transcriptional terminator element of human gastrin gene, which is the only element characterized to date in terms of its function in transcriptional termination, increases the transient expression levels of recombinant proteins. The expression of the beta-galactosidase gene was enhanced 3-4-fold in HeLa cells by inserting the terminator element of human gastrin gene at th...

Fluorescein-di-beta-D-galactopyranoside (FDG) was found to be a useful substrate for beta-galactosidase detection by flow cytometry in gram-negative bacteria, since it entered viable cells and gave a fluorescence emission proportional to the enzymatic activity. C12-FDG, a more lipophilic derivative, gave a very poor signal because of the lack of penetration. On the contrary, C12-FDG was more se...