PMID- 7951051
OWN - NLM
STAT- MEDLINE
DCOM- 19941128
LR  - 20171116
IS  - 1039-9712 (Print)
IS  - 1039-9712 (Linking)
VI  - 33
IP  - 2
DP  - 1994 May
TI  - Ammonium ions stimulate in vitro the activity of phosphoenolpyruvate carboxylase 
      from leaves of Amaranthus hypochondriacus, a C4 plant: evidence for allosteric 
      activation.
PG  - 337-43
AB  - Ammonium ions stimulated in vitro the activity of PEP carboxylase (PEPC) 
      extracted from dark-adapted leaves of Amaranthus hypochondriacus. Maximum 
      stimulation of 80 to 85% occurred at 50 microM ammonium chloride. There was a 
      marginal inhibition of PEPC at 5 mM ammonium chloride. Among several ions tested, 
      potassium ions stimulated PEPC to a limited extent of about 30%. In presence of 
      ammonium, there was no change either in the sensitivity of enzyme to malate or in 
      the affinity for substrate, PEP. On the other hand, glucose-6-phosphate, an 
      allosteric activator, which stimulated the enzyme by two-fold, could enhance PEPC 
      activity by < 20% in the presence of ammonium. The light-activated form of PEPC 
      from leaves of Amaranthus hypochondriacus was not stimulated, but was inhibited 
      in the presence of ammonium. Our results demonstrate that ammonium ions stimulate 
      PEPC by acting at the allosteric site. Ammonium ion being a component of plant 
      metabolism could be an important regulator of PEPC, particularly in C4 plants.
FAU - Gayathri, J
AU  - Gayathri J
AD  - School of Life Sciences, University of Hyderabad, India.
FAU - Raghavendra, A S
AU  - Raghavendra AS
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Biochem Mol Biol Int
JT  - Biochemistry and molecular biology international
JID - 9306673
RN  - 0 (Cations, Monovalent)
RN  - 0 (Glucosephosphates)
RN  - 0 (Plant Extracts)
RN  - 0 (Quaternary Ammonium Compounds)
RN  - 01Q9PC255D (Ammonium Chloride)
RN  - 56-73-5 (Glucose-6-Phosphate)
RN  - EC 4.1.1.31 (Phosphoenolpyruvate Carboxylase)
RN  - RWP5GA015D (Potassium)
SB  - IM
MH  - Allosteric Regulation
MH  - Ammonium Chloride/pharmacology
MH  - Cations, Monovalent/pharmacology
MH  - Enzyme Activation/drug effects
MH  - Glucose-6-Phosphate
MH  - Glucosephosphates/metabolism
MH  - Magnoliopsida/*enzymology
MH  - Phosphoenolpyruvate Carboxylase/*metabolism
MH  - Plant Extracts/metabolism
MH  - Potassium/pharmacology
MH  - Quaternary Ammonium Compounds/*pharmacology
EDAT- 1994/05/01 00:00
MHDA- 1994/05/01 00:01
CRDT- 1994/05/01 00:00
PHST- 1994/05/01 00:00 [pubmed]
PHST- 1994/05/01 00:01 [medline]
PHST- 1994/05/01 00:00 [entrez]
PST - ppublish
SO  - Biochem Mol Biol Int. 1994 May;33(2):337-43.