scholarly journals Allosteric and kinetic properties of L-lactate dehydrogenase from Thermus caldophilus GK24, an extremely thermophilic bacterium.

1985 ◽  
Vol 49 (2) ◽  
pp. 359-365 ◽  
Author(s):  
Hayao TAGUCHI ◽  
Masayuki MACHIDA ◽  
Hiroshi MATSUZAWA ◽  
Takahisa OHTA
Keyword(s):  
Lactate Dehydrogenase ◽  
Thermophilic Bacterium ◽  
Kinetic Properties ◽  
Thermus Caldophilus

scholarly journals l-mandelate dehydrogenase from Rhodotorula graminis: comparisons with the l-lactate dehydrogenase (flavocytochrome b2) from Saccharomyces cerevisiae

1993 ◽  
Vol 290 (1) ◽  
pp. 103-107 ◽  
Author(s):  
O Smékal ◽  
M Yasin ◽  
C A Fewson ◽  
G A Reid ◽  
S K Chapman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactate Dehydrogenase ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Dimensional Structure ◽  
Striking Difference ◽  
Kinetic Properties ◽  
Proton Abstraction ◽  
Rate Determining Step ◽  
Kinetic Isotope

L-Lactate dehydrogenase (L-LDH) from Saccharomyces cerevisiae and L-mandelate dehydrogenase (L-MDH) from Rhodotorula graminis are both flavocytochromes b2. The kinetic properties of these enzymes have been compared using steady-state kinetic methods. The most striking difference between the two enzymes is found by comparing their substrate specificities. L-LDH and L-MDH have mutually exclusive primary substrates, i.e. the substrate for one enzyme is a potent competitive inhibitor for the other. Molecular-modelling studies on the known three-dimensional structure of S. cerevisiae L-LDH suggest that this enzyme is unable to catalyse the oxidation of L-mandelate because productive binding is impeded by steric interference, particularly between the side chain of Leu-230 and the phenyl ring of mandelate. Another major difference between L-LDH and L-MDH lies in the rate-determining step. For S. cerevisiae L-LDH, the major rate-determining step is proton abstraction at C-2 of lactate, as previously shown by the 2H kinetic-isotope effect. However, in R. graminis L-MDH the kinetic-isotope effect seen with DL-[2-2H]mandelate is only 1.1 +/- 0.1, clearly showing that proton abstraction at C-2 of mandelate is not rate-limiting. The fact that the rate-determining step is different indicates that the transition states in each of these enzymes must also be different.

scholarly journals INFLUÊNCIA DA TEMPERATURA E DO pH NAS PROPRIEDADES CINÉTICAS DA LACTATO DESIDROGENASE DO MÚSCULO EPAXIAL DE Prochilodus scropha e Notothenia neglecta

1998 ◽  
Vol 3 (1) ◽  
Author(s):  
CLEONI SANTOS CARVALHO ◽  
RUBENS ROSA ◽  
KIKUE T. SASSAKI ◽  
METRY BACILA
Keyword(s):  
Lactate Dehydrogenase ◽  
Ph Effect ◽  
Antarctic Fish ◽  
Tropical Fish ◽  
Effect Of Temperature ◽  
Kinetic Properties ◽  
Activation Effect ◽  
Nad Oxidoreductase ◽  
The Antarctic ◽  
Epaxial Muscle

Foi levado a efeito um estudo comparativo das propriedades cinéticas da lactico desidrogenase (Llactato NAD+ oxidorreductase, E.C.1.1.1.27) purificada do músuclo epaxial do peixe tropical Prochilodus scropha e do peixe antártico Notothenia neglecta. Os seguintes parâmetros foram estudados: a. Efeito do pH; efeito da temperatura e valores para a energia de ativação; efeito da concentração de substrato e o efeito da temperatura sobre os valores de Km. Abstract It has been carried out a comparative study on the kinetic properties of the lactate dehydrogenase (L-lactate NAD+ oxidoreductase, E.C.1.1.1.27) purified from the epaxial muscle of the tropical fish Prochilodus scropha and the Antarctic fish Notothenia neglecta. The following parameters were studied: a. Effect of pH; effect of temperature and values for energy of activation; effect of substrate concentration and the effect of temperature on the Km values.

A comparative analysis of the evolutionary patterning and mechanistic bases of lactate dehydrogenase thermal stability in porcelain crabs, genus Petrolisthes

2001 ◽  
Vol 204 (4) ◽  
pp. 767-776
Author(s):  
J.H. Stillman ◽  
G.N. Somero
Keyword(s):  
Thermal Stability ◽  
Comparative Analysis ◽  
Lactate Dehydrogenase ◽  
Protein Interactions ◽  
Kinetic Properties ◽  
Post Translational Modification ◽  
Extrinsic Factors ◽  
Thermal Stability Of ◽  
Interspecific Diversity

The kinetic properties of orthologous homologs (orthologs) of enzymes are typically correlated with environmental temperatures in species adapted to different thermal regimes, but correlations between adaptation temperature and enzyme thermal stability are less clear. Although the thermal stability of a protein is related chiefly to its primary structure (including post-translational modification), thermal stability can also be altered by extrinsic factors present in the intracellular milieu. Here, we present a comparative analysis of the thermal stability of lactate dehydrogenase (LDH) orthologs from 22 congeneric species of porcelain crab (genera Petrolisthes and Allopetrolisthes) from a broad range of thermal habitats. Interspecific diversity of LDH stability is high: temperatures required for a 50 % loss of activity in 10 min ranged from 65 to 75.5 degrees C, corresponding to half-lives of less than 1 min to more than 3 h at 70 degrees C. Although stability is positively correlated with maximal habitat temperature in some sister taxa, phylogenetic comparative analysis incorporating all 22 species does not indicate that the interspecific diversity of LDH stability represents an adaptive response to current thermal habitats. Examination of the mechanistic bases of LDH stabilization indicates that differences in stability are related both to properties of the LDH molecule itself (intrinsic stability) and to the effects of extrinsic protein(s). Intrinsic differences were shown by the unfolding of structure during heating, as measured by circular dichroism spectroscopy. Stabilizing effects of extrinsic proteins are implied by the results of cellular fractionation experiments that removed low-molecular-mass solutes and proteins from the muscle homogenates. We conclude that the overall structural stability and functional properties of proteins can evolve independently and that in vivo protein-protein interactions can provide another means to regulate protein stability selectively.

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