scholarly journals Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase

1978 ◽  
Vol 173 (2) ◽  
pp. 483-496 ◽  
Author(s):  
C S Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Substrate Inhibition ◽  
Kinetic Studies ◽  
Primary Alcohols ◽  
Reductive Methylation ◽  
Factors Affecting ◽  
Liver Alcohol Dehydrogenase ◽  
Wide Range ◽  
Lysine Residues ◽  
Michaelis Constants

Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.

scholarly journals Horse liver alcohol dehydrogenase. A study of the essential lysine residue

1975 ◽  
Vol 149 (3) ◽  
pp. 627-635 ◽  
Author(s):  
S S Chen ◽  
P C Engel
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rate Constant ◽  
Lysine Residue ◽  
Horse Liver Alcohol Dehydrogenase ◽  
First Order ◽  
Liver Alcohol Dehydrogenase ◽  
Horse Liver ◽  
Lysine Residues ◽  
Modified Enzyme ◽  
Covalent Complex

1. The inactivation of horse liver alcohol dehydrogenase by pyridoxal 5'-phosphate in phosphate buffer, pH8, at 10°C was investigated. Activity declines to a minimum value determined by the pyridoxal 5'-phosphate concentration. The maximum inactivation in a single treatment is 75%. This limit appears to be set by the ratio of the first-order rate constants for interconversion of inactive covalently modified enzyme and a readily dissociable non-covalent enzyme-modifier complex. 2. Reactivation was virtually complete on 150-fold dilution: first-order analysis yielded an estimate of the rate constant (0.164min-1), which was then used in the kinetic analysis of the forward inactivation reaction. This provided estimates for the rate constant for conversion of non-covalent complex into inactive enzyme (0.465 min-1) and the dissociation constant of the non-covalent complex (2.8 mM). From the two first-order constants, the minimum attainable activity in a single cycle of treatment may be calculated as 24.5%, very close to the observed value. 3. Successive cycles of modification followed by reduction with NaBH4 each decreased activity by the same fraction, so that three cycles with 3.6 mM-pyridoxal 5'-phosphate decreased specific activity to about 1% of the original value. The absorption spectrum of the enzyme thus treated indicated incorporation of 2-3 mol of pyridoxal 5'-phosphate per mol of subunit, covalently bonded to lysine residues. 4. NAD+ and NADH protected the enzyme completely against inactivation by pyridoxal 5'-phosphate, but ethanol and acetaldehyde were without effect. 5. Pyridoxal 5'-phosphate used as an inhibitor in steady-state experiments, rather than as an inactivator, was non-competitive with respect to both NADH and acetaldehyde. 6. The partially modified enzyme (74% inactive) showed unaltered apparent Km values for NAD+ and ethanol, indicating that modified enzyme is completely inactive, and that the residual activity is due to enzyme that has not been covalently modified. 7. Activation by methylation with formaldehyde was confirmed, but this treatment does not prevent subsequent inactivation with pyridoxal 5'-phosphate. Presumably different lysine residues are involved. 8. It is likely that the essential lysine residue modified by pyridoxal 5'-phosphate is involved either in binding the coenzymes or in the catalytic step. 9. Less detailed studies of yeast alcohol dehydrogenase suggest that this enzyme also possesses an essential lysine residue.

Kinetic Studies with Liver Alcohol Dehydrogenase*

Biochemistry ◽  
1965 ◽  
Vol 4 (11) ◽  
pp. 2442-2451 ◽  
Author(s):  
Craig C. Wratten ◽  
W. W. Cleland
Keyword(s):  
Alcohol Dehydrogenase ◽  
Kinetic Studies ◽  
Liver Alcohol Dehydrogenase

Relative reactivities of primary alcohols as substrates of liver alcohol dehydrogenase

1968 ◽  
Vol 46 (4) ◽  
pp. 381-385 ◽  
Author(s):  
C. S. Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rate Equation ◽  
Electronic Effect ◽  
Graphical Analysis ◽  
Primary Alcohols ◽  
Structural Requirement ◽  
Liver Alcohol Dehydrogenase ◽  
Polar Groups ◽  
Kinetic Coefficients ◽  
Kinetics Of

To obtain information concerning the general structural requirement of alcohols as substrates of liver alcohol dehydrogenase, the kinetics of the enzymic oxidation of primary alcohols were studied. All the active substrates possess hydrophobic side groups. Introduction of polar groups renders alcohols inactive or inhibitory. To correlate reactivities of primary alcohols as substrates with the nature of their side groups, their relative reactivities are expressed in terms of kinetic coefficients which were solved from the rate equation by successive graphical analysis. Based on kinetic results, the relative reactivities of primary alcohols as substrates of liver alcohol dehydrogenase are discussed in relation to the hydrophobic interaction and the electronic effect of their side groups.

scholarly journals Kinetics and reaction mechanism of yeast alcohol dehydrogenase with long-chain primary alcohols

1976 ◽  
Vol 157 (1) ◽  
pp. 15-22 ◽  
Author(s):  
W Schöpp ◽  
H Aurich
Keyword(s):  
Alcohol Dehydrogenase ◽  
Dissociation Constants ◽  
Kinetic Studies ◽  
Random Order ◽  
Primary Alcohols ◽  
Yeast Alcohol Dehydrogenase ◽  
Kinetic Coefficients ◽  
Non Linear ◽  
High Concentrations ◽  
Long Chain

Kinetic studies of yeast alcohol dehydrogenase with NAD+ and ethanol, hexanol or decanol as substrates invariably result in non-linear Lineweaver-Burk plots if the alcohol is the variable substrate. The kinetic coefficients determined from secondary plots are consistent with an ‘equilibrium random-order‘ mechanism for extremely low alcohol concentrations and for all alcohols, the transformation of the ternary complexes being the rate-limiting step of the reaction. This mechanism also applies to long-chain substrates at high concentrations, whereas the rate of the ethanol-NAD+ reaction at high ethanol concentrations is determined by the dissociation of the enzyme-NADH complex. The dissociation constants for the enzyme-NAD+ complex and for the enzyme-alcohol complexes obtained from the kinetic quotients satisfactorily correspond to the dissociation constants obtained by use of other techniques. It is suggested that the non-linear curves may be attributed to a structural change in the enzyme itself, caused by the alcohol.

The Preparation of Some Biochemically Important Aldehydes

1975 ◽  
Vol 53 (8) ◽  
pp. 920-922 ◽  
Author(s):  
R. Julian S. Duncan
Keyword(s):  
Alcohol Dehydrogenase ◽  
Horse Liver Alcohol Dehydrogenase ◽  
Liver Alcohol Dehydrogenase ◽  
Horse Liver ◽  
Michaelis Constants

Methods for the preparation of 3,4-dihydroxyphenylacetaldehyde, 4-hydroxy-3-methoxyphenylacetaldehyde, and 3,4-dihydroxyphenylglycolaldehyde are described. Michaelis constants and maximal velocities for the reduction of a number of biologically important aldehydes by horse liver alcohol dehydrogenase and NADH are tabulated.

scholarly journals The dye-linked alcohol dehydrogenase of Rhodopseudomonas acidophila. Comparison with dye-linked methanol dehydrogenases

1978 ◽  
Vol 169 (3) ◽  
pp. 677-686 ◽  
Author(s):  
C W Bamforth ◽  
J R Quayle
Keyword(s):  
Alcohol Dehydrogenase ◽  
Aliphatic Amines ◽  
Primary Alcohols ◽  
Ph Optimum ◽  
Rhodopseudomonas Acidophila ◽  
Wide Range ◽  
The Stability ◽  
Phenazine Methosulphate ◽  
Primary Aliphatic Amines

1. A dye-linked alcohol dehydrogenase was purified 20-fold from extracts of Rhodopseudomonas acidophila 10050 grown anaerobically in the light on methanol/HCO3-. 2. The enzyme resembled many previously reported methanol dehydrogenases from other methylotrophic organisms in coupling to phenazine methosulphate, requiring ammonia as an activator, possessing a pH optimum of 9 and a mol.wt. of approx. 116000. In many other respects the enzyme showed singular properties. 3. The stability of the enzyme under various conditions of temperature and pH was studied. 4. Primary aliphatic amines containing up to nine carbon atoms (the longest tested) were better activators than ammonia. 5. A wide range of primary alcohols and aldehydes served as substrates, with apparent Km values ranging from 57 mM for methanol to 6 micron for ethanol. 6. O2 was an inhibitor competitive with respect to the alcohol substrate. In the presence of O2, apparent Km values of 145 mM were recorded for methanol. 6. Cyanide and alphaalpha'-bipyridine were inhibitors competitive with respect to the amine activator. 7. The properties of the enzyme from Rhodopseudomonas acidophila are compared with those of similar enzymes from other organisms, and implications of the salient differences are discussed.

Purification and kinetic characterization of pickerel liver alcohol dehydrogenase with dual coenzyme specificity

1993 ◽  
Vol 71 (9-10) ◽  
pp. 421-426 ◽  
Author(s):  
Loola S. Al-Kassim ◽  
C. Stan Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Gel Filtration ◽  
Kinetic Studies ◽  
Resonance Spectroscopy ◽  
Coenzyme Specificity ◽  
Liver Alcohol Dehydrogenase ◽  
Steady State Kinetic ◽  
Dehydrogenase Isozyme ◽  
State Kinetic

A major alcohol dehydrogenase isozyme that displays dual coenzyme specificity has been purified from pickerel liver by ion-exchange, gel filtration, and affinity chromatographic procedures. The purified enzyme is chromatographically and electrophoretically homogeneous. It is dimeric and possesses common physical properties shared by other liver alcohol dehydrogenases. Phosphorus-31 nuclear magnetic resonance spectroscopy demonstrates that NADP+ binds to two coenzyme sites of the pickerel enzyme. Steady-state kinetic studies suggest that pickerel liver alcohol dehydrogenase catalyzes NAD(P)+-linked ethanol oxidation via a random pathway. While the NADP+ reduction involves the formation of an abortive complex at high NADP+ concentrations, the NAD+ reduction at low NAD+ concentrations follows an ordered Bi-Bi mechanism with NAD+ being the leading reactant.Key words: purification, pickerel liver, alcohol dehydrogenase.

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