The anomeric specificity of β-galactosidase and lac permease from Escherichia coli

1981 ◽  
Vol 59 (2) ◽  
pp. 100-105 ◽  
Author(s):  
R. E. Huber ◽  
K. L. Hurlburt ◽  
C. L. Turner
Keyword(s):  
Escherichia Coli ◽  
Glycosidic Bond ◽  
Lac Operon ◽  
Acceptor Reaction ◽  
Glucose Release ◽  
Bond Breakage ◽  
Lactose Metabolism ◽  
Anomeric Specificity

β-Galactosidase was found to act on α-lactose slightly more than twice as rapidly as on β-lactose for both the hydrolysis and transgalactosylis reactions. The effect was shown to be on the Vmax values; the Km values for the different anomeric forms were the same. The step of the reaction for which the enzyme has anomeric specificity was shown to be glycosidic bond breakage. The steps in glucose release or in the glucose acceptor reaction were not affected by anomeric composition. Neither allolactose hydrolysis nor transport of lactose into the cells by lac permease was sensitive to the anomeric composition of the substrate. The implications of these results for lac operon induction and for lactose metabolism are discussed.

scholarly journals Lac Operon Boolean Models: Dynamical Robustness and Alternative Improvements

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 600 ◽  
Author(s):  
Marco Montalva-Medel ◽  
Thomas Ledger ◽  
Gonzalo A. Ruz ◽  
Eric Goles
Keyword(s):  
Escherichia Coli ◽  
Limit Cycles ◽  
The Other ◽  
Lac Operon ◽  
Boolean Models ◽  
Bistable Behavior

In Veliz-Cuba and Stigler 2011, Boolean models were proposed for the lac operon in Escherichia coli capable of reproducing the operon being OFF, ON and bistable for three (low, medium and high) and two (low and high) parameters, representing the concentration ranges of lactose and glucose, respectively. Of these 6 possible combinations of parameters, 5 produce results that match with the biological experiments of Ozbudak et al., 2004. In the remaining one, the models predict the operon being OFF while biological experiments show a bistable behavior. In this paper, we first explore the robustness of two such models in the sense of how much its attractors change against any deterministic update schedule. We prove mathematically that, in cases where there is no bistability, all the dynamics in both models lack limit cycles while, when bistability appears, one model presents 30% of its dynamics with limit cycles while the other only 23%. Secondly, we propose two alternative improvements consisting of biologically supported modifications; one in which both models match with Ozbudak et al., 2004 in all 6 combinations of parameters and, the other one, where we increase the number of parameters to 9, matching in all these cases with the biological experiments of Ozbudak et al., 2004.

scholarly journals Transcription of the lac Operon of Escherichia coli

1974 ◽  
Vol 249 (20) ◽  
pp. 6556-6561
Author(s):  
Terrance G. Cooper ◽  
Boris Magasanik
Keyword(s):  
Escherichia Coli ◽  
Lac Operon

The role of lac operon and lac repressor in the induction using lactose for the expression of periplasmic human interferon-α2b by Escherichia coli

2011 ◽  
Vol 62 (4) ◽  
pp. 1427-1435 ◽  
Author(s):  
Joo Shun Tan ◽  
Ramakrishnan Nagasundara Ramanan ◽  
Tau Chuan Ling ◽  
Shuhaimi Mustafa ◽  
Arbakariya B. Ariff
Keyword(s):  
Escherichia Coli ◽  
Lac Repressor ◽  
Human Interferon ◽  
Lac Operon ◽  
Interferon Α2b

Carbon-13 NMR investigation of the anomeric specificity of CMP-N-acetylneuraminic acid synthetase from Escherichia coli

Biochemistry ◽  
1992 ◽  
Vol 31 (3) ◽  
pp. 775-780 ◽  
Author(s):  
Michael G. Ambrose ◽  
Stephen J. Freese ◽  
Mary S. Reinhold ◽  
Thomas G. Warner ◽  
Willie F. Vann
Keyword(s):  
Escherichia Coli ◽  
Acetylneuraminic Acid ◽  
Anomeric Specificity

scholarly journals The Escherichia coli dnaJ mutation affects biosynthesis of specific proteins, including those of the lac operon.

1987 ◽  
Vol 169 (5) ◽  
pp. 1917-1922 ◽  
Author(s):  
M Ohki ◽  
H Uchida ◽  
F Tamura ◽  
R Ohki ◽  
S Nishimura
Keyword(s):  
Escherichia Coli ◽  
Lac Operon ◽  
Specific Proteins

scholarly journals Cloning and Heterologous Expression of Plantaricin ZJ5, a Novel Bacteriocin from Lactobacillus plantarum ZJ5, in Escherichia coli

2018 ◽  
Vol 13 (12) ◽  
pp. 1934578X1801301
Author(s):  
Dafeng Song ◽  
Ping Li ◽  
Qing Gu
Keyword(s):  
Escherichia Coli ◽  
Fusion Protein ◽  
Lactobacillus Plantarum ◽  
Micrococcus Luteus ◽  
Biologically Active ◽  
Biological Method ◽  
Lac Operon ◽  
E Coli ◽  
First Time ◽  
Soluble Material

A novel bacteriocin, plantaricin ZJ5 (PZJ5) was yielded from Lactobacillus plantarum ZJ5, cloned, and produced in Escherichia coli BL21 (DE3) pLys. The PZJ5 structural gene was fused with a Trx tag, and cloned into the pET32a plasmid under the control of the inducible lac operon. Induction was performed with isopropyl-β-D-thiogalactopyranoside (IPTG), with subsequent overexpression of the fusion protein, followed by purification to homogeneity via His affinity chromatography. Recombinant E. coli produced greater quantities of PZJ5 than L. plantarum ZJ5, and PZJ5 in E. coli was expressed in the form of soluble material. Biologically active PZJ5 was recovered by cleaving the purified fusion protein using enterokinase. The released PZJ5 demonstrated antibacterial activity against Micrococcus luteus. In this study, an inexpensive biological method using a Trx fusion system was presented, and for the first time, bacteriocin PZJ5 was expressed and purified in E. coli.

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