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21.
Structure and expression of the overlapping ND4L and ND5 genes of Neurospora crassa mitochondria 总被引:1,自引:0,他引:1
Summary Genes homologous to the mammalian mitochondrial NADH dehydrogenase subunit genes ND4L and ND5 were identified in the mitochondrial genome of the filamentous fungus Neurospora crassa, and the structure and expression of these genes was examined. The ND4L gene (interrupted by one intervening sequence) potentially encodes an 89 residue long hydrophobic protein that shares about 26% homology (or 41% homology if conservative amino acid substitutions are allowed) with the analogous human mitochondrial protein. The ND5 gene (which contains two introns) encodes a 715 residue polypeptide that shares 23% homology with the human analogue; a 300 amino acid long region is highly conserved (50% homology) in the two ND5 proteins. The stop codon of the ND4L gene overlaps the initiation codon of the downstream ND5 gene, and the two genes are contranscribed and probably cotranslated. A presumed mature dicistronic (ND4L plus ND5) RNA was detected. The postulated mRNA (about 3.2 kb) contains 5 and 3 non-coding regions of about 86 and 730 nucleotides, respectively; this species is generated from very large precursor RNAs by a complex processing pathway. The ND4L and ND5 introns are all stable after their excision from the precursor species.Abbreviations bp
base pairs
- rRNA
ribosomal RNA
- ND
NADH dehydrogenase
- URF
unidentified reading frame
- kDal
kilodaltons; a.a., amino acid 相似文献
22.
Maize (Zea mays L.) seeds differ in their relative tolerance to the anaerobic environment caused by flooding. Seed tolerance to flooding
stress depends on cellular and metabolic processes since gross anatomical responses have not developed at the pre-emergence
stage. The study reported here characterizes the activities of four anaerobic respiratory enzymes: pyruvate decarboxylase
(PDC), alcohol dehydrogenase (ADH), lactate dehydrogenase (LDH), and malic enzyme (ME) in the flood-tolerant A632 and floodsusceptible
Mo 17 inbred maize seeds during flooding at 10 and 25°C. Each inbred consisted of two seed lots possessing 95% and 75% germination
levels. Flooding increased the activities of all four enzymes. However, no consistent correlation between anaerobic enzyme
activity and flood tolerance was observed across genotype, seed quality and flooding temperature. The results indicate that
it may not be feasible to use whole-seed anaerobic enzyme activities to predict maize seed performance under flooding stress.
Contribution from the Soil Drainage Research Unit, USDA-ARS, Columbus, OH, in cooperation with the Ohio Agricultural Research
and Development Center, The Ohio State University. OARDC Journal Article No. 66–86. 相似文献
23.
Glycollate dehydrogenase of the halotolerant green alga Dunaliella salina, isolated from a brine pond, was found associated with the membrane fraction which exhibited complete photosynthetic activity. Highest enzyme activity was found in cells grown in the presence of 5% NaCl. Any increase in NaCl concentration led to a decrease in specific enzyme activity.Abbreviations PSI(II)
photosystem I(II) 相似文献
24.
Activity of key nitrogen assimilating enzymes was studied in developing grains of high-lysine opaque sorghum P-721 and normal
sorghum CSV-5. The higher percentage of protein in opaque sorghum was mainly due to lower starch content since protein per
grain was less than in CSV-5. During grain development, albufn and globulin decreased while prolafne and glutelin increased.
Prolafne content in CSV-5 was higher than in opaque sorghum. Average nitrate reductase activity in flag and long leaf were
similar in both the varieties. The nitrate reductase activity decreased during grain development. Glutamate dehydrogenase
activity was higher during early development and lower at later stages in opaque sorghum than in CSV-5. Glutamate oxaloacetate
transaminase activity was higher and glutamine synthetase lower in opaque sorghum than in CSV-5 grains during development.
Glutamate synthase activity was higher in opaque sorghum up to day 20 and lower thereafter than in CSV-5. It is suggested
that reduced activities of glutamine synthetase as well as glutamate synthase in opaque sorghum as compared to CSV-5 during
later stages of development may restrict protein accumulation in the former. 相似文献
25.
Thomas K. C. Leung Christine Hall Clinton Monfries Louis Lim 《Journal of neurochemistry》1987,49(1):232-238
Neurone-specific enolase (NSE) and the brain form of creatine phosphokinase (CPK-BB) were previously found to be present in rat synaptosomal plasma membranes (SPM) using two-dimensional gel (2-D gel) and peptide analysis; enzymatic activities of these and of pyruvate kinase (PK), all involved in ATP generation, were shown to be "cryptic" unless the SPM were treated with Triton X-100. We now show that enzymatic activation also occurs when the SPM are treated with trifluoperazine (TFP). TFP activation occurred even when the enzymes were membrane associated, showing that solubilization was not responsible for "unmasking" the enzyme activities. When TFP treatment was performed at alkaline instead of neutral pH, NSE and CPK-BB were released as well as PK, nonneuronal enolase, and aldolase which were identified by 2-D gel and tryptic peptide analysis. Other proteins released included calmodulin, actin, and the 70-kilodalton heat-shock cognate protein. Tubulin, synapsin I, and a 35-kilodalton basic protein were largely unaffected. The latter was identified as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase on the basis of 2-D gel and peptide analyses and subsequent partial sequencing of a rat brain cDNA coding for the same protein. TFP treatment is thus useful for activating latent enzymes as well as for distinguishing enzymes that have a different disposition on the membrane. 相似文献
26.
Purification and characterization of the Danish (skive) variant of mouse liver alcohol dehydrogenase
Douglas K. Rex William F. Bosron Francis Dwulet Ting-Kai Li 《Biochemical genetics》1987,25(1-2):111-121
The partially inbred Danish (Skive) strain of mice exhibits a form of liver alcohol dehydrogenase (ADH) which differs in electrophoretic mobility from that of all other inbred mouse strains thus far examined, e.g., C57BL/10, DBA/2J, and BALB/c. In order to compare the catalytic and molecular properties of the variant and normal enzyme forms, they were purified to homogeneity by ion-exchange and affinity chromatography. Tryptic peptides of reduced and carboxymethylated subunits of the normal and variant ADH forms were mapped by thin-layer two-dimensional electrophoresis and chromatography and by reversed-phase high-performance liquid chromatography. A unique nonapeptide in the Danish mouse liver ADH which did not appear in enzymes from C57BL/10, DBA/2J, or BALB/c mice was identified by both methods. Amino acid sequencing of this peptide revealed that the Arg residue at position 124, as predicted from the cDNA sequence of ADH in DBA/2J mice, has been replaced by Leu in the Danish variant. The Leu for Arg substitution in the variant form appears to account for its decreased cathodic mobility with electrophoresis in starch gels at pH 7.2. The K
m
and V
max
of ADH from the Danish strain for three primary alcohols and three aldehydes were similar in value to those of ADH from the C57BL/10, DBA/2J, and BALB/c strains. Based on the X-ray structure of horse liver ADH, position 124 is on the solvent-exposed surface of the catalytic domain. The finding that the kinetic constants are similar for the normal and variant forms is consistent with the observation that this residue is not in the active site and that there is no known role for it in the ADH catalytic mechanism.This work was supported by NIAAA Grant AA-04307. 相似文献
27.
During growth on glycerol two marine Desulfovibrio strains that can grow on an unusually broad range of substrates contained high activities of glycerol kinase, NAD(P)-independent glycerol 3-phosphate dehydrogenase and the other enzymes necessary for the conversion of dihydroxyacetone phosphate to pyruvate. Glycerol dehydrogenase and a specific dihydroxyacetone kinase were absent. During growth on dihydroxyacetone, glycerol kinase is involved in the initial conversion of this compound to dihydroxyacetone phosphate which is then further metabolized. Some kinetic properties of the partially purified glycerol kinase were determined. The role of NAD as electron carrier in the energy metabolism during growth of these strains on glycerol and dihydroxyacetone is discussed.Glycerol also supported growth of three out of four classical Desulfovibrio strains tested. D. vulgaris strain Hildenborough grew slowly on glycerol and contained glycerol kinase, glycerol 3-phosphate dehydrogenase and enzymes for the dissimilation of dihydroxyacetone phosphate. In D. gigas which did not grow on glycerol the enzymes glycerol kinase and glycerol 3-phosphate dehydrogenase were absent in lactate-grown cells.Abbreviations DHA
dihydroxyacetone
- DHAP
dihydroxyacetone phosphate
- G3P
glycerol 3-phosphate
- GAP
glyceraldehyde 3-phosphate
- 3-PGA
3-phosphoglycerate
- 2-PGA
2-phosphoglycerate
- 2,3-DPGA
2,3-diphosphoglycerate
- PEP
phosphoenolpyruvate
- DH
dehydrogenase
- GK
glycerol kinase
- DHAK
dihydroxyacetone kinase
- TIM
triosephosphate isomerase
- PGK
3-phosphoglycerate kinase
- PK
pyruvate kinase
- LDH
lactate dehydrogenase
- DTT
dithiotreitol
- HEPES
4-(2-hydroxyethyl)-1-piperazine ethane sulfonic acid
- PIPES
piperazine-1,1-bis(2-ethane sulfonic acid)
- BV2+/BV+
oxidized/reduced benzylviologen
- PMS
phenazine methosulfate
- DCPIP
2,6-dichlorophenolindophenol
- MTT
3-(4,5-dimethylthiazol-2-yl)-2,4-diphenyltetrazolium bromide 相似文献
28.
Summary The complete nucleotide sequence of the Salmonella strain LT2 gnd gene for 6-phosphogluconate dehydrogenase was determined. The gene contains 1404 bases and encodes a 468 amino acid polypeptide, which is the same as for Escherichia coli K12. The DNA sequence shows 14.8% difference between the two and the amino acid sequence 3.6% difference. Changes are mostly in the third codon base and most of the amino acid changes are conservative. 相似文献
29.
30.
The development of mitochondrial NAD+ -malate dehydrogenase (EC 1.1.1.37) in mung bean and cucumber cotyledons was followed. using the antibody raised against it, during and following germination. The developmental patterns were quite different between the two. In cucumber, the content of mitochondrial malate dehydrogenase continued to increase through 3–4 days after the beginning of imbibition. This was, at least in part, due to active synthesis of the enzyme protein, and the synthesis seemed to be regulated by the availability of the translatable mRNA for the enzyme. In mung bean, on the other hand, the enzyme was present in dry cotyledons at a rather high concentration, and remained at a constant level between day 1 and day 3 after the reduction of the content to one-half its initial level during the first day. De novo synthesis of the enzyme could not be detected in mung bean cotyledons by pulse-labeling experiment. 相似文献