Human liver alcohol dehydrogenase an enzyme essential to the metabolism of digitalis.
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Alcohol Oxidoreductases↗
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Results for “essential enzymes”
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T4 DNA topoisomerase: a new ATP-dependent enzyme essential for initiation of T4 bacteriophage DNA replication.
A novel ATP-dependent DNA topoisomerase which makes reversible double-strand breaks in the DNA double helix has been purified to near homogeneity from T4 bacteriophage-infected Escherichia coli cells. Genetic data suggest that this activity is essential for initiating T4 DNA replication forks in vivo.
Adenosine Triphosphate↗
Differential inhibition of phosphodiesterase according to the organ origin of the enzyme.
Essential differences in the degree of papaverine [5 x 10(-5) M]- and theophylline [1 x 10(-3) M]-induced inhibition of cyclic nucleotide phosphodiesterase (PDE) were found in homogenates from different structures of the CNS as well as from different organs of male albino rats. Both inhibitors of PDE showed a mosaic pattern of their inhibitory effects on the enzyme activity of the brain structures tested. Papaverine inhibited PDE by 36 percent in the spinal cord, 53 percent in the cerebellum, 56 percent in the cortex, and 75 percent in the brain stem. Theophylline inhibited PDE least in the cerebellum (26 percent ) and most markedly in the brain stem (68 percent). Still larger differences were observed in the inhibitory action of papaverine and theophylline on PDE of the organs tested (e.g., papaverine inhibited PDE by 6 percent in the heart and 73 percent in the spleen; theophylline inhibited PDE by 26 percent in the adrenals and by 72 percent in the heart. The mosaic sensitivity of PDE in different organs and brain structures to papaverine and theophylline was considered as an expression of isoenzyme heterogeneity.
Animals↗
The effect of cadmium on soluble proteins, enzymes, and essential metals of the duodenal mucosa.
In this study, it was observed that Cd administration had effects on metal distribution and enzyme activities and induced metallothionein in the soluble fraction of the duodenal mucosa. Wistar rats were given water containing 100 ppm of Cd ad libitum for 30 days. Cd treatment caused a significant increase in the mucosal weight and in the soluble protein. The existence of metallothionein was apparent and 40% of the soluble Cd was bound to the thionein. Most of the remaining Cd was bound to the larger proteins. The activities of isocitrate dehydrogenase (ICDH) and glucose-6-phosphate dehydrogenase (G6PDH) enzymes, localized in the soluble fraction, were significantly increased by Cd ingestion. The increase of Zn and the decrease of Mn and Mg were also observed in the soluble fraction of the duodenal mucosa.
Adenosine Triphosphatases↗
Targeting Borrelia burgdorferi HtpG with a berserker molecule, a strategy for anti-microbial development.
Conventional antimicrobial discovery relies on targeting essential enzymes in pathogenic organisms, contributing to a paucity of new antibiotics to address resistant strains. Here, by targeting a non-essential enzyme, Borrelia burgdorferi HtpG, to deliver lethal payloads, we expand what can be considered druggable within any pathogen. We synthesized HS-291, an HtpG inhibitor tethered to the photoactive toxin verteporfin. Reactive oxygen species, generated by light, enables HS-291 to sterilize Borrelia cultures by causing oxidation of HtpG, and a discrete subset of proteins in proximity to the chaperone. This caused irreversible nucleoid collapse and membrane blebbing. Tethering verteporfin to the HtpG inhibitor was essential, since free verteporfin was not retained by Borrelia in contrast to HS-291. For this reason, we liken HS-291 to a berserker, wreaking havoc upon the pathogen's biology once selectively absorbed and activated. This strategy expands the druggable pathogenic genome and offsets antibiotic resistance by targeting non-essential proteins.
Borrelia burgdorferi↗
DNA polymerase I: essential replication enzyme.
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DNA Nucleotidyltransferases↗
Enzyme histochemistry of cultured ovarian cells. III. Histochemical characteristics of bovine granulosa and theca interna cells grown separately in cell culture.
Granulosa and theca interna cells were isolated from bovine preovulatory ovarian follicles. They were cultured separately but in the same conditions of cell culture. Both cell types, grown as monolayers, were investigated histochemically with special regard to the activity of several hydroxysteroid dehydrogenases: delta53betaOH-SDH, 17betaOH-SDH, 20alphaOH-SDH and G6P-DH. Bovine granulosa and theca interna cells during in vitro culture showed high activity of delta53betaOH-SDH and G6P-DH, the enzymes essential to progesterone biosynthesis. Enzyme pattern of cultured cells indicated continuation in vitro of luteinization, which in the normal preovulatory follicle of the bovine ovary begins prior to ovulation. There was investigated as well the influence of single doses of gonadotrophic hormones and estradiol on growth, lipid contents and enzymic activity of cultured in vitro bovine granulosa and theca interna cells.
17-Hydroxysteroid Dehydrogenases↗
[Research technics of enzymes used in the diagnosis of gram negative bacteria (author's transl)].
The enzymes used in the identification of Gram negative bacteria belonging to the families of Enterobacteriaceae, Vibrionaceae, Parvobacteriaceae, Pseudomonadaceae and to the genera Alteromonas, Xanthomonas, Alkaligenes, Flavobacterium are classified arbitrarily by the author into enzymes essential for the diagnosis of the family (oxidase, nitratase), enzymes useful in the diagnosis of the genus or the species (ONPG-hydrolase, urease, oxidative desaminase, lysine decarboxylase and ornithine, arginine dihydrolase, thiosulphate reductase, pectinase), and into enzymes sought to confirm the diagnosis (tetrathionate reductase, gelatinase, lipase, DNase, amylase, beta-xylosidase, lecithinase). The technics permitting their identification are described and their distribution in the species and genera studied is reported.
Bacteria↗
Combined decrease of postheparin-diamine oxidase (histaminase) and postheparin-lipoproteinlipase in inflammatory diseases.
Diamine oxidase (DAO, histaminase), according to Schayer, is an essential enzyme in histamine metabolism. It metabolises also a variety of diamines such as putrescine and cadaverine and is generally accepted to be identical with histaminase. Lipoproteinlipase (LL) is assumed to play an essential role in lipid metabolism. In vertebrates, parenterally applied heparin causes a marked dose-dependent rise of the plasma level of both enzymes mainly due to the release from the enzyme containing organs. The plasmatic level changes of DAO and LL after heparin application (200 U/kg b.wt., i.v.) have been studied in 30 patients suffering from 20 different, predominantly inflammatory diseases. In all cases the release of postheparin diamine oxidase (PHD) and of post-heparin lipoproteinlipase (PHLA) was found to be markedly decreased. There existed a highly significant correlation between the degree of the release of both enzymes (r=0.843, p less than 0.0005). In all patients normal levels of plasma insulin were detected. No correlation was found between PHLA and plasma triglycerides levels. Decrease of PHD respectively PHLA was a more sensitive biochemical parameter than were changes of serum glutamic pyruvic transaminase in acute hepatitis and of C reactive protein (CRP) in chronic inflammatory kidney diseases. This finding is most likely a general phenomenon in inflammatory diseases. Besides hormonal regulation inflammation-dependent effects on PHLA have to be discussed.
Adult↗
[Nuclease from Aspergillus oryzae, specific for single-stranded regions of nucleic acids].
A single-stranded specific nuclease has been purified from amyloryzine obtained from the mould fungi Aspergillus cryzae. The nuclease under study resembles the enzymes described in the literature in its ability to hydrolyze single-stranded nucleic acids. However, the enzyme essentially differs from previously known nucleases in some catalytic properties, particularly in its ability for degradation of poly A. It has been shown that the enzyme also hydrolyzes the synthetic dinucleotide pTpT to mononucleoside phosphates.
Aspergillus↗
The action of chelating agents on human liver aldehyde dehydrogenase.
Human liver aldehyde dehydrogenase was inhibited by aromatic chelating agents. However, structurally related compounds with much lower metal-complexing ability displayed affinities for enzyme essentially equal to those of their respective chelating analogues. Inhibition was competitive with respect to the coenzyme. It is suggested that hydrophobic interactions between the inhibitors and the coenzyme-binding site of the enzyme are responsible for the observed effects on activity.
2,2'-Dipyridyl↗
PARP1 UFMylation ensures the stability of stalled replication forks.
The S-phase checkpoint involving CHK1 is essential for fork stability in response to fork stalling. PARP1 acts as a sensor of replication stress and is required for CHK1 activation. However, it is unclear how the activity of PARP1 is regulated. Here, we found that UFMylation is required for the efficient activation of CHK1 by UFMylating PARP1 at K548 during replication stress. Inactivation of UFL1, the E3 enzyme essential for UFMylation, delayed CHK1 activation and inhibits nascent DNA degradation during replication blockage as seen in PARP1-deficient cells. An in vitro study indicated that PARP1 is UFMylated at K548, which enhances its catalytic activity. Correspondingly, a PARP1 UFMylation-deficient mutant (K548R) and pathogenic mutant (F553L) compromised CHK1 activation, the restart of stalled replication forks following replication blockage, and chromosome stability. Defective PARP1 UFMylation also resulted in excessive nascent DNA degradation at stalled replication forks. Finally, we observed that PARP1 UFMylation-deficient knock-in mice exhibited increased sensitivity to replication stress caused by anticancer treatments. Thus, we demonstrate that PARP1 UFMylation promotes CHK1 activation and replication fork stability during replication stress, thus safeguarding genome integrity.
DNA Replication↗
Functional divergence of two soybean cytosolic serine hydroxymethyltransferases in development and defense against soybean cyst nematode.
Serine hydroxymethyltransferase (SHMT) is an enzyme essential for one-carbon metabolism. In higher plants, multiple SHMT genes code for isoforms that function in the cytosol, nucleus, mitochondria, and chloroplasts. The soybean genome contains two cytosolic SHMTs, GmSHMT05 and GmSHMT08, sharing high sequence identity and similar expression throughout soybean development. In certain soybean genotypes, two amino acid substitutions negatively impact GmSHMT08's ability to bind to tetrahydrofolate (THF), leading to a gain-of-function in resistance to the soybean cyst nematode (SCN). Whether this perturbation to the enzyme has other functional consequences for soybean growth and development remains unknown. Here, we investigated the roles of cytosolic GmSHMTs in soybean growth and development. We determined that the 3D structure and folate-binding affinity of GmSHMT05 are highly similar to the version of GmSHMT08 found in susceptible soybeans. We further measured phenotypic traits of two ethyl methanesulfonate-derived Gmshmt08 mutant plants in an SCN-resistant soybean background. Aboveground soybean growth and development were similar, except the Gmshmt08 mutant plants showed a significant increase in pods/plant in field phenotyping trials. Belowground analyses revealed a significant increase in lateral root and total root length in mutant plants, and CRISPR-Cas9 editing demonstrated an essential role of cytosolic SHMTs in root growth. Taken together, our results indicate that GmSHMT05 sustains overall soybean growth and development in the absence of GmSHMT08; however, GmSHMT08's gain-of-function in SCN resistance negatively influences pod and root growth, highlighting a potential trade-off between soybean defense and development that may impact yield when breeding with GmSHMT08 to develop SCN-resistant varieties.
1-C folate metabolism↗
Thermosensitive mutation in Escherichia coli simultaneously causing defects in penicillin-binding protein-1Bs and in enzyme activity for peptidoglycan synthesis in vitro.
A thermosensitive mutant of Escherichia coli K-12 was isolated in which the membrane fractions were deficient both in penicillin-binding protein-1Bs, the major components of protein 1 [Spratt, B.G. & Pardee, A.B. (1975) Nature 254, 516-517] and in activity for in vitro peptidoglycan synthesis. The mutant was also supersensitive to many kinds of beta-lactam antibiotics. All these phenotypic changes were found to be caused by a single mutation (mrc). Genetic mapping studies show that the mrc mutation was located at about 3.3 min on the E. coli chromosome linkage map [Bachmann, B.J., Low, K.B. & Taylor, A.L. (1976) Bacteriol. Rev. 40, 116-167]. Penicillin-binding protein-1Bs seemed to be identical to one of the essential enzymes involved in crosslinking of peptidoglycan and the target of cell-lytic action of penicillins. Possible functions of some other penicillin-binding proteins in compensating for lack of protein-1Bs were also proposed.
Bacterial Proteins↗
An analysis of the kinetic positions held by five enzymes of carbohydrate metabolism in Dictyostelium discoideum.
The role of five enzymes essential to differentiation in Dictyostelium discoideum has been analyzed by simulation studies and ranked with respect to their over-all effect on the conversion of glycogen to cellulose and trehalose in the later stages of differentiation. Their order is, in decreasing effectiveness, (a) glycogen phosphorylase, (b and c) cellulose and trehalose synthetase, (d) UDP-glucose pyrophosphorylase and (e) glycogen synthetase. Glycogen phosphorylase controls the speed of differentiation, which can also be slightly modified by the level of glycogen synthetase. The cellulose and trehalose synthetases and UDP-glucose pyrophosphorylase control the relative concentrations of trehalose and cellulose. The final trehalose to cellulose ratio is also affected by the speed of differentiation. Compensatory interaction between enzymes affecting the outcome of differentiation is also analyzed.
Cellulose↗
[Alpha 1 antitrypsin deficiency in childhood].
The author deals with the clinical importance of the alpha-1-antitrypsin deficiency in form of a survey with tabular representation of own cases. Alpha-1-antitrypsin as an inactivator of proteolytically effective enzymes essentially participates in the localised effect of proteinases. A genetically determined decreased alpha-1-antitrypsin serum level (= alpha-1-antitrypsin deficiency) by this causally participates in the pathogenesis of certain hepatopathies and in the pulmonary emphysema appearing already at the carly adult age. Within differential-diagnostic considerations an alpha-1-antitrypsin deficiency should be excluded in: 1. etiologically unclear cholestasis in infancy, 2. etiologically unclear hepatopathy in childhood, and in 3. early emphysema.
Adult↗
Natural premature protein synthesis termination can be reduced in Escherichia coli by decreased translation rates.
Peptidyl tRNA hydrolase is an essential enzyme for normal growth inasmuch as a mutant strain of Escherichia coli with a temperature-sensitive hydrolase cannot continue protein synthesis at the non-permissive temperature. In the absence of hydrolase peptidyl tRNA rapidly accumulates. Why peptidyl tRNA should be formed is the subject of this report. The rapid rate of protein synthesis is likely one mechanism of formation of peptidyl tRNA. A strA mutant of the hydrolase (pth-1) mutant strain that has a 40% reduction in amino acid polymerization rate can grow at 42 degrees C. StrA mutants with normal polymerization rates, however, cannot grow at 42 degrees C when pth-1 is present. Furthermore, addition of low levels of chloramphenicol (2--4 micrograms/ml) but not several other tested drugs, phenotypically suppressed pth-1 at 42 degrees C. Chloramphenicol, at these concentrations, was found to reduce the amino acid polymerization rate 30--40%. On the other hand, no evidence could be found that amino acyl tRNA selection errors are incorporated into pseudo revertants of the pth-1 strain.
Bacterial Proteins↗
The oxidation of cytochrome c peroxidase by hydrogen peroxide. Characterization of products.
H2O2 reacts with cytochrome c peroxidase in a variety of ways. The initial reaction produces cytochrome c peroxidase Compound I. If more than a 10-fold excess of H2O2 is added to the enzyme, a portion of the H2O2 will react with Compound I to produce molecular oxygen. The remainder oxidizes the heme group and various amino acid residues in the protein. If less than a 10-fold excess of H2O2 is added to the enzyme, essentially all the H2O2 is utilized by oxidation of amino acid residues in the protein. The oxidation of the amino acid residues by H2O2 substantially modifies the reactivity of cytochrome c peroxidase. The modification of reactivity could be the direct result of amino acid oxidation or an indirect result caused by a perturbation of the protein structure at the active site. The products oxidized at pH 8 lose their ability to react with H2O2. The products oxidized at pH4 react with H2O2 but their reactivity toward Fe(CN)4-6 is substantially reduced.
Cytochrome c Group↗