scholarly journals An Electrophoretically Cryptic Alcohol Dehydrogenase Variant in Drosophila melanogaster. III. Biochemical Properties and Comparison with Common Enzyme Forms

1981 ◽  
Vol 34 (6) ◽  
pp. 625 ◽  
Author(s):  
GK Chambers ◽  
AV Wilks ◽  
JB Gibson

The biochemical properties of the heat-stable alcohol dehydrogenase variant ADH-FCh.D. have been investigated and compared with those of the two common enzyme forms ADH-F and ADH-S. The results show that ADH-F and ADH-S differ with respect to substrate specificity, their response to high concentrations of secondary alcohols and their apparent Michaelis constants for three alcohols in two different buffer systems. In all these tests the enzyme ADH-FCh.D. resembles ADH-S much more closely than ADH-F.

1988 ◽  
Vol 251 (1) ◽  
pp. 223-227 ◽  
Author(s):  
J O Winberg ◽  
J S McKinley-McKee

The NAD+ + acetone-induced isoenzyme conversion of the Drosophila melanogaster AdhS alleloenzyme was studied. Absorption and fluorescence spectra as well as electrophoretic and kinetic methods show that the conversion process proceeds through three steps. Initially a binary enzyme-NAD+ complex is formed, followed by a ternary enzyme-NAD+-acetone complex with a KEO, Ac of 1.7 M. The last step is a rate-limiting irreversible process in which NAD+ and acetone are covalently linked to the enzyme. A Vm of 2.4 min-1 was obtained at pH 8.6.


1981 ◽  
Vol 23 (2) ◽  
pp. 305-313 ◽  
Author(s):  
Steven M. Anderson ◽  
John F. McDonald

The results of an analysis of the biochemical basis of changes in alcohol dehydrogenase (E.C.1.1.1.1) activity over Drosophila development are presented. The data indicate that (1) the characteristic changes that occur in ADH activity over development are predominantly, if not exclusively, the result of quantitative changes in the amount of enzyme present rather than qualitative changes affecting the enzyme's specific activity and (2) the fluctuations in amount of ADH which occur during development are not the result of the only known form of post-translational modification capable of affecting the biochemical properties of the enzyme. We conclude that developmental changes in amount of ADH are most likely the result of fluctuations in the turnover of the ADH protein.


Author(s):  
Pieter W.H. Heinstra ◽  
Karel Th. Eisses ◽  
Willem Scharloo ◽  
George E.W. Thörig

1998 ◽  
Vol 329 (3) ◽  
pp. 561-570 ◽  
Author(s):  
Jan-Olof WINBERG ◽  
John S. McKINLEY-McKEE

Drosophila alcohol dehydrogenase (Adh) catalyses the oxidation of both alcohols and aldehydes. In the latter case, the oxidation is followed by a reduction of the aldehyde, i.e. a dismutation reaction. At high pH, dismutation is accompanied by a small release of NADH, which is not observed at neutral pH. Previously it has been emphasized that kinetic coefficients obtained by measuring the increase in A340, i.e. the release of NADH at high pH is not a direct measure of the aldehyde oxidation reaction and these values cannot be compared with those for alcohol dehydrogenation. In this article we demonstrate that this is not entirely true, and that the coefficients ϕB and ϕAB, where B is the aldehyde and A is NAD+, are the same for a dismutation reaction and a simple aldehyde dehydrogenase reaction. Thus the substrate specificity of the aldehyde oxidation reaction can be determined by simply measuring the NADH release. The coefficients for oxidation and dehydrogenation reactions (ɸ0d and ϕAd respectively) are complex and involve the constants for the dismutation reaction. However, dead-end inhibitors can be used to determine the quantitative contribution of the kinetic constants for the aldehyde oxidation and reduction pathways to the ϕ0d and ϕAd coefficients. The combination of dead-end and product inhibitors can be used to determine the reaction mechanism for the aldehyde oxidation pathway. Previously, we showed that with Drosophila Adh, the interconversion between alcohols and aldehydes followed a strictly compulsory ordered pathway, although aldehydes and ketones formed binary complexes with the enzyme. This raised the question regarding the reaction mechanism for the oxidation of aldehydes, i.e. whether a random ordered pathway was followed. In the present work, the mechanism for the oxidation of different aldehydes and the accompanying dismutation reaction with the slow alleloenzyme (AdhS) from Drosophila melanogaster has been studied. To obtain reliable results for the liberation of NADH during the initial-rate phase, the reaction was measured with a sensitive recording filter fluorimeter, and the complexes formed with the different dead-end and product inhibitors have been interpreted on the basis of a full dismutation reaction. The results are only consistent with a compulsory ordered reaction mechanism, with the formation of a dead-end binary enzyme-aldehyde complex. Under initial-velocity conditions, the rate of acetate release was calculated to be larger than 2.5 s-1, which is more than ten times that of NADH. The substrate specificity constant (kcat/Km or 1/ϕB) with respect to the oxidation of substrates was propan-2-ol > ethanol > acetaldehyde > trimethylacetaldehyde.


Genetics ◽  
1980 ◽  
Vol 96 (4) ◽  
pp. 927-938
Author(s):  
David R Wilcox ◽  
Satya Prakash

ABSTRACT Twenty-six D. pseudoobscura strains isogenic for xanthine dehydrogenase alleles from Mesa Verde, Colorado, were tested for differences in the biochemical properties of different allelic forms of xanthine dehydrogenase. No significant differences in binding affinity (Km) or substrate specificity of the enzyme were found. Significant variation among strains, in activity (V  max) and among electromorphs, as well as among strains, in thermolability was found. For the few strains tested, the activity and thermolability differences were shown to co-segregate with the electrophoretic mobility of the variant allele.


Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 677
Author(s):  
John Onolame Unuofin

Laccase is increasingly adopted in diverse industrial and environmental applications, due to its readily accessible requirements for efficient catalytic synthesis and biotransformation of chemicals. However, it is perceived that its industrial production might incur some unfavorable overhead, which leads to expensive market products, and the corresponding negative environmental feedback, due to the use of capital-intensive and precarious chemicals. To this end, this study was designed to evaluate the performance indicators of the valorization of wheat bran by a novel Jb1b laccase and its subsequent application in waste minimization and water management, on a laboratory scale. Optimal Jb1b laccase was produced in submerged fermentation medium containing wheat bran, an agroindustrial residue, through response surface methodology (RSM) algorithm, and was applied in dye decolorization and denim bioscouring, respectively. Results showed that the resultant enzyme manifested unique biochemical properties, such as enhanced tolerance at certain physicochemical conditions, with a residual activity of at least ca. 76%. Furthermore, phenomenally high concentrations of synthetic dyes (0.2% w v−1) were decolorized over 56 h, and a 6 h mediator-supported simultaneous denim bleaching and decolorization of wash effluent was observed. The sustainability of the production and application processes were inferred from the reusability of the fermentation sludge as a potential biofertilizer, with subsequent prospects for the biostimulation and bioaugmentation of contaminated soils, whereas the decolorized water could be adopted for other uses, amongst which horticulture and forestry are typical examples. These phenomena therefore authenticate the favorable environmental feedbacks and overhead realized in this present study.


Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 897-911 ◽  
Author(s):  
S McNabb ◽  
S Greig ◽  
T Davis

Abstract This report describes the structure and expression of the outspread (osp) gene of Drosophila melanogaster. Previous work showed that chromosomal breakpoints associated with mutations of the osp locus map to both sides of the alcohol dehydrogenase gene (Adh), suggesting that Adh and the adjacent gene Adh' are nested in osp. We extended a chromosomal walk and mapped additional osp mutations to define the maximum molecular limit of osp as 119 kb. We identified a 6-kb transcript that hybridizes to osp region DNA and is altered or absent in osp mutants. Accumulation of this RNA peaks during embryonic and pupal periods. The osp cDNAs comprise two distinct classes based on alternative splicing patterns. The 5′ end of the longest cDNA was extended by PCR amplification. When hybridized to the osp walk, the 5′ extension verifies that Adh and Adh' are nested in osp and shows that osp has a transcription unit of ≥74 kb. In situ hybridization shows that osp is expressed both maternally and zygotically. In the ovary, osp is transcribed in nurse cells and localized in the oocyte. In embryos, expression is most abundant in the developing visceral and somatic musculature.


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