scholarly journals Kinetics of CO Insertion and Acetyl Group Transfer Steps, and a Model of the Acetyl-CoA Synthase Catalytic Mechanism

2006 ◽  
Vol 128 (37) ◽  
pp. 12331-12338 ◽  
Author(s):  
Xiangshi Tan ◽  
Ivan V. Surovtsev ◽  
Paul A. Lindahl
Keyword(s):  
Catalytic Mechanism ◽  
Acetyl Coa ◽  
Group Transfer ◽  
Co Insertion ◽  
Acetyl Group ◽  
Kinetics Of

Kinetics of acetyl-CoA synthetase—I. Mode of addition of substrates

1975 ◽  
Vol 6 (8) ◽  
pp. 537-542 ◽  
Author(s):  
William W. Farrar ◽  
Kent M. Plowman
Keyword(s):  
Acetyl Coa ◽  
Kinetics Of

scholarly journals The extended reductive acetyl-CoA pathway: ATPases in metal cluster maturation and reductive activation

2014 ◽  
Vol 395 (5) ◽  
pp. 545-558 ◽  
Author(s):  
Jae-Hun Jeoung ◽  
Sebastian Goetzl ◽  
Sandra Elisabeth Hennig ◽  
Jochen Fesseler ◽  
Christina Wörmann ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Metal Cluster ◽  
Potential Gradient ◽  
Reductive Activation ◽  
Acetyl Coa ◽  
Oxygen Sensitive ◽  
Metal Organic ◽  
Acetyl Group ◽  
Acetyl Coa Pathway ◽  
Atp Binding And Hydrolysis

Abstract The reductive acetyl-coenzyme A (acetyl-CoA) pathway, also known as the Wood-Ljungdahl pathway, allows reduction and condensation of two molecules of carbon dioxide (CO2) to build the acetyl-group of acetyl-CoA. Productive utilization of CO2 relies on a set of oxygen sensitive metalloenzymes exploiting the metal organic chemistry of nickel and cobalt to synthesize acetyl-CoA from activated one-carbon compounds. In addition to the central catalysts, CO dehydrogenase and acetyl-CoA synthase, ATPases are needed in the pathway. This allows the coupling of ATP binding and hydrolysis to electron transfer against a redox potential gradient and metal incorporation to (re)activate one of the central players of the pathway. This review gives an overview about our current knowledge on how these ATPases achieve their tasks of maturation and reductive activation.

THE KINETICS OF AMINO GROUP TRANSFER BY CORN RADICLE TRANSAMINASE

1957 ◽  
Vol 35 (12) ◽  
pp. 1289-1303 ◽  
Author(s):  
F. S. Cook
Keyword(s):  
Classical Theory ◽  
Spectrophotometric Method ◽  
Substrate Concentration ◽  
Enzyme Preparation ◽  
Reaction Rate ◽  
Amino Group ◽  
Group Transfer ◽  
Kinetics Of ◽  
Published Account

The kinetics of transamination are complicated by the presence of two substrates whose concentrations change appreciably during the course of the reaction. The only previously published account of the kinetics of this system deviates considerably from classical theory. Equations based on premises of Michaelis and Menten have been shown, however, to accommodate the data on reaction rate in relation to substrate concentration obtained with a corn radicle enzyme preparation by a spectrophotometric method.

Structural effects on epimerization of bacteriochlorophyll a and chlorophyll a revealed using 3-acetyl chlorophyll a

2020 ◽  
Vol 24 (04) ◽  
pp. 499-504 ◽  
Author(s):  
Yoshitaka Saga ◽  
Shiori Nakagawa
Keyword(s):  
Physicochemical Properties ◽  
Chlorophyll A ◽  
Photosynthetic Reaction Center ◽  
Molecular Structures ◽  
Structural Factors ◽  
Structural Effects ◽  
Photosynthetic Organisms ◽  
Acetyl Group ◽  
Kinetics Of

Chlorophyll (Chl) and bacteriochlorophyll (BChl) pigments, which are crucial cyclic tetrapyrroles in photosynthesis, generally have a chiral center in their exo-cyclic five-membered E-ring. Although [Formula: see text]-epimers (primed-type) of (B)Chl pigments are rarely present in photosynthetic organisms, they play key roles in photosynthetic reaction center complexes. The epimerization mechanism of (B)Chl pigments in vivo has not been unraveled. The structural effects on the physicochemical properties of (B)Chl epimerization reactions provide useful information to tackle this question. We analyzed epimerization of three pigments, BChl [Formula: see text], Chl [Formula: see text], and 3-acetyl Chl [Formula: see text], to elucidate the structural factors that are responsible for epimerization reactions. We compared the epimerization kinetics of the three pigments and concluded that the bacteriochlorin skeleton (7,8,17,18-tetrahydroporphyrin) significantly retarded the epimerization kinetics. Thus, BChl [Formula: see text] exhibited slower epimerization kinetics than Chl [Formula: see text] in spite of the presence of the electron-withdrawing 3-acetyl group that accelerates epimerization. In contrast to the large structural effects of (B)Chl molecules on epimerization kinetics, the thermodynamic properties at equilibrium in the epimerization of the three pigments were barely influenced by their molecular structures. This study also demonstrates that a semi-synthetic pigment, 3-acetyl Chl [Formula: see text], is appropriate for comparative analyses of the structural effects of BChl [Formula: see text] and Chl [Formula: see text] on their physicochemical properties.

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