Substrate inhibition versus product feedback inhibition: In the perspective of single molecule enzyme kinetics

2021 ◽  
Author(s):  
Sharmistha Dhatt ◽  
Mintu Nandi ◽  
Pinaki Chaudhury
Keyword(s):  
Enzyme Kinetics ◽  
Single Molecule ◽  
Feedback Inhibition ◽  
Substrate Inhibition

Single molecule enzyme kinetics: application to myosin ATPases

1999 ◽  
Vol 27 (2) ◽  
pp. 33-37 ◽  
Author(s):  
C. R. Bagshaw ◽  
P. B. Conibear
Keyword(s):  
Enzyme Kinetics ◽  
Single Molecule

Direct Observation of Anomalous Single-Molecule Enzyme Kinetics

2005 ◽  
Vol 77 (14) ◽  
pp. 4374-4377 ◽  
Author(s):  
Hung-Wing Li ◽  
Edward S. Yeung
Keyword(s):  
Enzyme Kinetics ◽  
Direct Observation ◽  
Single Molecule

Single-molecule enzyme kinetics in the presence of inhibitors

2012 ◽  
Vol 137 (4) ◽  
pp. 045102 ◽  
Author(s):  
Soma Saha ◽  
Antara Sinha ◽  
Arti Dua
Keyword(s):  
Enzyme Kinetics ◽  
Single Molecule

Steady-state kinetics

2000 ◽  
Author(s):  
Athel Cornish-Bowden
Keyword(s):  
Steady State ◽  
Enzyme Kinetics ◽  
Single Molecule ◽  
Transient State ◽  
Curve Analysis ◽  
Rate Equations ◽  
Progress Curve ◽  
Steady State Kinetics ◽  
Time Regime ◽  
Time Courses

All of chemical kinetics is based on rate equations, but this is especially true of steady-state enzyme kinetics: in other applications a rate equation can be regarded as a differential equation that has to be integrated to give the function of real interest, whereas in steady-state enzyme kinetics it is used as it stands. Although the early enzymologists tried to follow the usual chemical practice of deriving equations that describe the state of reaction as a function of time there were too many complications, such as loss of enzyme activity, effects of accumulating product etc., for this to be a fruitful approach. Rapid progress only became possible when Michaelis and Menten (1) realized that most of the complications could be removed by extrapolating back to zero time and regarding the measured initial rate as the primary observation. Since then, of course, accumulating knowledge has made it possible to study time courses directly, and this has led to two additional subdisciplines of enzyme kinetics, transient-state kinetics, which deals with the time regime before a steady state is established, and progress-curve analysis, which deals with the slow approach to equilibrium during the steady-state phase. The former of these has achieved great importance but is regarded as more specialized. It is dealt with in later chapters of this book. Progress-curve analysis has never recovered the importance that it had at the beginning of the twentieth century. Nearly all steps that form parts of the mechanisms of enzyme-catalysed reactions involve reactions of a single molecule, in which case they typically follow first-order kinetics: . . . v = ka . . . . . . 1 . . . or they involve two molecules (usually but not necessarily different from one another) and typically follow second-order kinetics: . . . v = kab . . . . . . 2 . . . In both cases v represents the rate of reaction, and a and b are the concentrations of the molecules involved, and k is a rate constant. Because we shall be regarding the rate as a quantity in its own right it is not usual in steady-state kinetics to represent it as a derivative such as -da/dt.

scholarly journals On the Velocity of Enzymatic Reactions in Michaelis–Menten-Like Schemes (Ensemble and Single-Molecule Versions)

2020 ◽  
Vol 65 (5) ◽  
pp. 412 ◽  
Author(s):  
L. N. Christophorov
Keyword(s):  
Binding Site ◽  
Single Molecule ◽  
Substrate Inhibition ◽  
Enzymatic Reaction ◽  
Enzymatic Reactions ◽  
Reaction Velocity ◽  
Conformational Regulation ◽  
Regulatory Properties

In searching non-standard ways of conformational regulation, various Michaelis–Menten-like schemes attract relentless attention, resulting in sometimes too sophisticated considerations. With the example of monomeric enzymes possessing an only binding site, we define the minimal schemes capable of bearing peculiar regulatory properties like “cooperativity” or substrate inhibition. The simplest ways of calculating the enzymatic reaction velocity are exemplified, either in the ensemble or single-molecule case.

Divergence in enzyme regulation between Caenorhabditis elegans and human tyrosine hydroxylase, the key enzyme in the synthesis of dopamine

2011 ◽  
Vol 434 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Ana C. Calvo ◽  
Angel L. Pey ◽  
Antonio Miranda-Vizuete ◽  
Anne P. Døskeland ◽  
Aurora Martinez
Keyword(s):  
Caenorhabditis Elegans ◽  
Tyrosine Hydroxylase ◽  
Biochemical Characterization ◽  
Catalytic Domain ◽  
Feedback Inhibition ◽  
Substrate Inhibition ◽  
Enzyme Regulation ◽  
C Elegans ◽  
Key Enzyme ◽  
Human Orthologue

TH (tyrosine hydroxylase) is the rate-limiting enzyme in the synthesis of catecholamines. The cat-2 gene of the nematode Caenorhabditis elegans is expressed in mechanosensory dopaminergic neurons and has been proposed to encode a putative TH. In the present paper, we report the cloning of C. elegans full-length cat-2 cDNA and a detailed biochemical characterization of the encoded CAT-2 protein. Similar to other THs, C. elegans CAT-2 is composed of an N-terminal regulatory domain followed by a catalytic domain and a C-terminal oligomerization domain and shows high substrate specificity for L-tyrosine. Like hTH (human TH), CAT-2 is tetrameric and is phosphorylated at Ser35 (equivalent to Ser40 in hTH) by PKA (cAMP-dependent protein kinase). However, CAT-2 is devoid of characteristic regulatory mechanisms present in hTH, such as negative co-operativity for the cofactor, substrate inhibition or feedback inhibition exerted by catecholamines, end-products of the pathway. Thus TH activity in C. elegans displays a weaker regulation in comparison with the human orthologue, resembling a constitutively active enzyme. Overall, our data suggest that the intricate regulation characteristic of mammalian TH might have evolved from more simple models to adjust to the increasing complexity of the higher eukaryotes neuroendocrine systems.

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