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Title: Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate

Abstract

The generality of the mechanism based inhibition of P-enolpyruvate carboxylases (PEPCase) by P-enol-3-bromopyruvate (BrPEP) was tested by measuring its effects on the allosterically regulated enzyme from E. coli. In the presence of 1mM Mn/sup 2 +/, BrPEP appears to be a competitive inhibitor (K/sub i/ = 0.0087mM) of PEPCase. Incubation of 0.005mM PEPCase with 0.5mM (or 1.0mM)BrPEP along with H/sup 14/CO/sub 3//sup -/ and Mn/sup 2 +/, yielded, upon reduction with NaBH/sub 4/, a protein containing radioactivity in an amount approximately proportional to that expected from the loss of catalytic activity. At both a 25- and a 50-fold excess (0.5mM and 1.0mM, respectively) of BrPEP to PEPCase subunits, first order loss of activity occurred with k values of 5.24 x 10/sup -3/ min/sup -1/ and 1.03 x 10/sup -2/ min/sup -1/, respectively. At the lower concentration of BrPEP the inactivation process appeared to be reversible after 40 min with no further inhibition occurring even up to two hours of incubation. At the higher concentration of BrPEP, the rate of inhibition slowed dramatically after 50 min and appeared insignificant over the next hour. These data suggest that BrPEP irreversibly inactivates the E. coli PEP carboxylase, but that there may be considerablemore » dissociation of the product, Br-oxaloacetate, before irreversible binding occurs, and that the reduced rate of inactivation may be due to depletion of BrPEP.« less

Authors:
;
Publication Date:
Research Org.:
Howard Univ. College of Medicine, Washington, DC
OSTI Identifier:
6710363
Report Number(s):
CONF-8606151-
Journal ID: CODEN: FEPRA
Resource Type:
Conference
Journal Name:
Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
Additional Journal Information:
Journal Volume: 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CARBOXYLASE; ENZYME ACTIVITY; PYRUVIC ACID; BIOCHEMICAL REACTION KINETICS; CARBON 14 COMPOUNDS; ESCHERICHIA COLI; INHIBITION; TRACER TECHNIQUES; BACTERIA; CARBON-CARBON LYASES; CARBOXY-LYASES; CARBOXYLIC ACIDS; ENZYMES; ISOTOPE APPLICATIONS; KETO ACIDS; KINETICS; LABELLED COMPOUNDS; LYASES; MICROORGANISMS; ORGANIC ACIDS; ORGANIC COMPOUNDS; REACTION KINETICS; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Asem, K, and Smith, T E. Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate. United States: N. p., 1986. Web.
Asem, K, & Smith, T E. Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate. United States.
Asem, K, and Smith, T E. Thu . "Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate". United States.
@article{osti_6710363,
title = {Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate},
author = {Asem, K and Smith, T E},
abstractNote = {The generality of the mechanism based inhibition of P-enolpyruvate carboxylases (PEPCase) by P-enol-3-bromopyruvate (BrPEP) was tested by measuring its effects on the allosterically regulated enzyme from E. coli. In the presence of 1mM Mn/sup 2 +/, BrPEP appears to be a competitive inhibitor (K/sub i/ = 0.0087mM) of PEPCase. Incubation of 0.005mM PEPCase with 0.5mM (or 1.0mM)BrPEP along with H/sup 14/CO/sub 3//sup -/ and Mn/sup 2 +/, yielded, upon reduction with NaBH/sub 4/, a protein containing radioactivity in an amount approximately proportional to that expected from the loss of catalytic activity. At both a 25- and a 50-fold excess (0.5mM and 1.0mM, respectively) of BrPEP to PEPCase subunits, first order loss of activity occurred with k values of 5.24 x 10/sup -3/ min/sup -1/ and 1.03 x 10/sup -2/ min/sup -1/, respectively. At the lower concentration of BrPEP the inactivation process appeared to be reversible after 40 min with no further inhibition occurring even up to two hours of incubation. At the higher concentration of BrPEP, the rate of inhibition slowed dramatically after 50 min and appeared insignificant over the next hour. These data suggest that BrPEP irreversibly inactivates the E. coli PEP carboxylase, but that there may be considerable dissociation of the product, Br-oxaloacetate, before irreversible binding occurs, and that the reduced rate of inactivation may be due to depletion of BrPEP.},
doi = {},
journal = {Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)},
number = ,
volume = 45:6,
place = {United States},
year = {1986},
month = {5}
}

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