Steady-state kinetic mechanism of rat tyrosine hydroxylase

Biochemistry ◽  
1991 ◽  
Vol 30 (15) ◽  
pp. 3658-3662 ◽  
Author(s):  
Paul F. Fitzpatrick
Keyword(s):  
Steady State ◽  
Tyrosine Hydroxylase ◽  
Kinetic Mechanism ◽  
Steady State Kinetic ◽  
State Kinetic

scholarly journals Steady-state kinetic mechanism of the NADP+- and NAD+-dependent reactions catalysed by betaine aldehyde dehydrogenase from Pseudomonas aeruginosa

2000 ◽  
Vol 352 (3) ◽  
pp. 675-683 ◽  
Author(s):  
Roberto VELASCO-GARCÍA ◽  
Lilian GONZÁLEZ-SEGURA ◽  
Rosario A. MUÑOZ-CLARES
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Steady State ◽  
Aldehyde Dehydrogenase ◽  
Substrate Inhibition ◽  
Kinetic Mechanism ◽  
Betaine Aldehyde Dehydrogenase ◽  
Betaine Aldehyde ◽  
Metabolic Role ◽  
Steady State Kinetic ◽  
State Kinetic

Betaine aldehyde dehydrogenase (BADH) catalyses the irreversible oxidation of betaine aldehyde to glycine betaine with the concomitant reduction of NAD(P)+ to NADP(H). In Pseudomonas aeruginosa this reaction is a compulsory step in the assimilation of carbon and nitrogen when bacteria are growing in choline or choline precursors. The kinetic mechanisms of the NAD+- and NADP+-dependent reactions were examined by steady-state kinetic methods and by dinucleotide binding experiments. The double-reciprocal patterns obtained for initial velocity with NAD(P)+ and for product and dead-end inhibition establish that both mechanisms are steady-state random. However, quantitative analysis of the inhibitions, and comparison with binding data, suggest a preferred route of addition of substrates and release of products in which NAD(P)+ binds first and NAD(P)H leaves last, particularly in the NADP+-dependent reaction. Abortive binding of the dinucleotides, or their analogue ADP, in the betaine aldehyde site was inferred from total substrate inhibition by the dinucleotides, and parabolic inhibition by NADH and ADP. A weak partial uncompetitive substrate inhibition by the aldehyde was observed only in the NADP+-dependent reaction. The kinetics of P. aeruginosa BADH is very similar to that of glucose-6-phosphate dehydrogenase, suggesting that both enzymes fulfil a similar amphibolic metabolic role when the bacteria grow in choline and when they grow in glucose.

scholarly journals Steady-State Kinetic Analysis of Phosphotransacetylase from Methanosarcina thermophila

2006 ◽  
Vol 188 (3) ◽  
pp. 1155-1158 ◽  
Author(s):  
Sarah H. Lawrence ◽  
James G. Ferry
Keyword(s):  
Steady State ◽  
Kinetic Analysis ◽  
Random Order ◽  
Kinetic Mechanism ◽  
Methanosarcina Thermophila ◽  
Steady State Kinetic ◽  
Ping Pong ◽  
Acetyl Group ◽  
State Kinetic ◽  
Reversible Transfer

ABSTRACT Phosphotransacetylase (EC 2.3.1.8) catalyzes the reversible transfer of the acetyl group from acetyl phosphate to coenzyme A (CoA), forming acetyl-CoA and inorganic phosphate. A steady-state kinetic analysis of the phosphotransacetylase from Methanosarcina thermophila indicated that there is a ternary complex kinetic mechanism rather than a ping-pong kinetic mechanism. Additionally, inhibition patterns of products and a nonreactive substrate analog suggested that the substrates bind to the enzyme in a random order. Dynamic light scattering revealed that the enzyme is dimeric in solution.

Enoyl-ACP Reductase (FabI) of Haemophilus influenzae: Steady-State Kinetic Mechanism and Inhibition by Triclosan and Hexachlorophene

2001 ◽  
Vol 390 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Jovita Marcinkeviciene ◽  
Wenjun Jiang ◽  
Lisa M Kopcho ◽  
Gregory Locke ◽  
Ying Luo ◽  
...  
Keyword(s):  
Steady State ◽  
Haemophilus Influenzae ◽  
Kinetic Mechanism ◽  
Steady State Kinetic ◽  
Enoyl Acp Reductase ◽  
State Kinetic

Steady-State Kinetic Mechanism and Reductive Half-Reaction ofd-Arginine Dehydrogenase fromPseudomonas aeruginosa

Biochemistry ◽  
2010 ◽  
Vol 49 (44) ◽  
pp. 9542-9550 ◽  
Author(s):  
Hongling Yuan ◽  
Guoxing Fu ◽  
Phillip T. Brooks ◽  
Irene Weber ◽  
Giovanni Gadda
Keyword(s):  
Steady State ◽  
Kinetic Mechanism ◽  
Steady State Kinetic ◽  
State Kinetic

scholarly journals Steady-state Kinetic Mechanism of PDK1

2006 ◽  
Vol 281 (31) ◽  
pp. 21670-21681 ◽  
Author(s):  
Xinxin Gao ◽  
Thomas K. Harris
Keyword(s):  
Steady State ◽  
Kinetic Mechanism ◽  
Steady State Kinetic ◽  
State Kinetic

Steady-State Kinetic Mechanism of Escherichia coli UDP-N-Acetylenolpyruvylglucosamine Reductase

Biochemistry ◽  
1995 ◽  
Vol 34 (16) ◽  
pp. 5390-5402 ◽  
Author(s):  
Adil M. Dhalla ◽  
Joseph Yanchunas ◽  
Hsu-Tso Ho ◽  
Paul Falk ◽  
Joseph J. Villafranca ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Kinetic Mechanism ◽  
Steady State Kinetic ◽  
State Kinetic

scholarly journals Altering kinetic mechanism and enzyme stability by mutagenesis of the dimer interface of glutathione reductase

1995 ◽  
Vol 312 (2) ◽  
pp. 527-533 ◽  
Author(s):  
A Bashir ◽  
R N Perham ◽  
N S Scrutton ◽  
A Berry
Keyword(s):  
Steady State ◽  
Glutathione Reductase ◽  
Enzyme Stability ◽  
Alpha Helix ◽  
Kinetic Mechanism ◽  
Wild Type ◽  
Dimer Interface ◽  
Kinetic Behaviour ◽  
Steady State Kinetic ◽  
State Kinetic

In wild-type glutathione reductase from Escherichia coli residues Val421 and Ala422 are located in an alpha-helix in a densely packed and hydrophobic region of the dimer interface, with their side chains packed against those of residues Ala422′ and Val421′ in the second subunit. A series of mutant glutathione reductases was constructed in which the identities of the residues at positions 421 and 422 were changed. Mutations were designed so as to present like charges (mutants Val421-->Glu:Ala422-->Glu and Val421-->Lys:Ala422-->Lys) or opposite charges (mutant Val421-->Lys:Ala422-->Glu) across the dimer interface to assess the role of electrostatic interactions in dimer stability. A fourth mutant (Val421-->His:Ala422-->His) was also constructed to investigate the effects of introducing a potentially protonatable bulky side chain into a crowded region of the dimer interface. In all cases, an active dimeric enzyme was found to be assembled but each mutant protein was thermally destabilized. A detailed steady-state kinetic analysis indicated that each mutant enzyme no longer displayed the Ping Pong kinetic behaviour associated with the wild-type enzyme but exhibited what was best described as a random bireactant ternary complex mechanism. This leads, depending on the chosen substrate concentration, to apparent sigmoidal, hyperbolic or complex kinetic behaviour. These experiments, together with others reported previously, indicate that simple mutagenic changes in regions distant from the active site can lead to dramatic switches in steady-state kinetic mechanism.

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