Another Enzyme (another + enzyme)

Distribution by Scientific Domains

Selected Abstracts

Stage-specific expression of Caenorhabditis elegans ribonuclease H1 enzymes with different substrate specificities and bivalent cation requirements

FEBS JOURNAL, Issue 2 2006
Hiromi Kochiwa
Ribonuclease H1 (RNase H1) is a widespread enzyme found in a range of organisms from viruses to humans. It is capable of degrading the RNA moiety of DNA,RNA hybrids and requires a bivalent ion for activity. In contrast with most eukaryotes, which have one gene encoding RNase H1, the activity of which depends on Mg2+ ions, Caenorhabditis elegans has four RNase H1-related genes, and one of them has an isoform produced by alternative splicing. However, little is known about the enzymatic features of the proteins encoded by these genes. To determine the differences between these enzymes, we compared the expression patterns of each RNase H1-related gene throughout the development of the nematode and the RNase H activities of their recombinant proteins. We found gene-specific expression patterns and different enzymatic features. In particular, besides the enzyme that displays the highest activity in the presence of Mg2+ ions, C. elegans has another enzyme that shows preference for Mn2+ ion as a cofactor. We characterized this Mn2+ -dependent RNase H1 for the first time in eukaryotes. These results suggest that there are at least two types of RNase H1 in C. elegans depending on the developmental stage of the organism. [source]

Analyses of ultraviolet-induced focus formation of hREV1 protein

GENES TO CELLS, Issue 3 2006
Yoshiki Murakumo
Translesional DNA synthesis (TLS) is one of the DNA damage tolerance mechanisms that allow cells with DNA damage to continue DNA replication. Each of the mammalian Y-family DNA polymerases (Pol ,, Pol ,, Pol ,, and REV1) has been shown to carry out TLS by itself or in combination with another enzyme in vitro. Recently, the C-terminal region of mammalian REV1 (the total 1251 residues in human) was found to interact with Pol ,, Pol ,, and Pol ,, as well as with the REV7 subunit of another TLS enzyme, Pol ,. Thus, it is proposed that REV1 plays a pivotal role in TLS in vivo. We here describe our study on the localization of human REV1 protein (hREV1) in nondamaged and ultraviolet (UV)-irradiated cells. Ectopically expressed hREV1 in mammalian cells was localized to the nucleus and exhibited dozens of tiny foci in approximately 3% of nondamaged cells. The percentage of focus-forming cells markedly increased after UV irradiation in a time- and dose-dependent manner. The focus formation was associated with UV-induced DNA damage. Interestingly, although the hREV1 foci in S-phase cells colocalized with PCNA foci, suggesting the association of hREV1 with the replication machinery, hREV1 focus formation was observed not only in the S phase but also outside S phase. Furthermore, it was found that the hREV1 focus formation after UV irradiation required a region near the C-terminal (826,1178). [source]

Effects of modification of membrane lipid composition on Bacillus subtilis sporulation and spore properties

K.K. Griffiths
Abstract Aims:, To determine effects of inner membrane lipid composition on Bacillus subtilis sporulation and spore properties. Methods and Results:, The absence of genes encoding lipid biosynthetic enzymes had no effect on B. subtilis sporulation, although the expected lipids were absent from spores' inner membrane. The rate of spore germination with nutrients was decreased c. 50% with mutants that lacked the major cardiolipin (CL) synthase and another enzyme for synthesis of a major phospholipid. Spores lacking the minor CL synthase or an enzyme essential for glycolipid synthesis exhibited 50,150% increases in rates of dodecylamine germination, while spores lacking enzymes for phosphatidylethanolamine (PE), phosphatidylserine (PS) and lysylphosphatidylglycerol (l-PG) synthesis exhibited a 30,50% decrease. Spore sensitivity to H2O2 and tert-butylhydroperoxide was increased 30,60% in the absence of the major CL synthase, but these spores' sensitivity to NaOCl or Oxone‘ was unaffected. Spores of lipid synthesis mutants were less resistant to wet heat, with spores lacking enzymes for PE, PS or l-PG synthesis exhibiting a two to threefold decrease and spores of other strains exhibiting a four to 10-fold decrease. The decrease in spore wet heat resistance correlated with an increase in core water content. Conclusions:, Changing the lipid composition of the B. subtilis inner membrane did not affect sporulation, although modest effects on spore germination and wet heat and oxidizing agent sensitivity were observed, especially when multiple lipids were absent. The increases in rates of dodecylamine germination were likely due to increased ability of this compound to interact with the spore's inner membrane in the absence of some CL and glycolipids. The effects on spore wet heat sensitivity are likely indirect, because they were correlated with changes in core water content. Significance and Impact of the Study:, The results of this study provide insight into roles of inner membrane lipids in spore properties. [source]

Effect of periodontal treatment on the activity of chitinase in whole saliva of periodontitis patients

G. J. Van Steijn
Human salivary chitinase could play a role in the defence against chitin-containing oral pathogens. The activity levels of chitinase in the whole saliva of periodontitis patients were significantly higher than those in saliva from controls. Periodontal treatment for a period of 5,6 months resulted in a three- to fourfold decrease in this enzyme activity. The activity of ,- N -acetylhexosaminidase, which is another enzyme that hydrolyses glycosidic linkages, also decreased as a result of treatment, although to a lesser extent. The decrease in chitinase activity upon treatment of the disease did not correlate with the decrease that was seen in clinical attachment loss and bleeding on probing, and only a weak correlation was observed with the changes in probing pocket depth and plaque index. No correlations were found between the above clinical parameters and the decrease in ,- N -acetylhexosaminidase activity. [source]

Plasma concentrations of haloperidol are related to CYP2D6 genotype at low, but not high doses of haloperidol in Korean schizophrenic patients

Hyung-Keun Roh
Aims, This study was carried out to evaluate the influence of CYP2D6 genotype on the steady state plasma concentrations of haloperidol and reduced haloperidol in Korean schizophrenic patients. Methods, One hundred and twenty Korean schizophrenic patients treated with various, clinically determined, doses of haloperidol (range 3,60, median 20 mg day,1) during monotherapy were recruited. CYP2D6 genotypes were determined by analysis of the CYP2D6*10 allele using allele-specific PCR and the CYP2D6*5 allele by long-PCR. Steady state plasma concentrations of haloperidol and reduced haloperidol were analysed by h.p.l.c. Results, Twenty-three (19.2%), 60 (50.0%), 1 (0.8%), 33 (27.5%) and 3 patients (2.5%) possessed the CYP2D6 genotypes *1/*1, *1/*10, *1/*5, *10/*10 and *10/*5, respectively. The allele frequencies of CYP2D6*1, *10 and *5 were 44.6%, 53.8% and 1.7%, respectively. Significant relationships between dose and plasma concentrations of haloperidol (linear; r2 = 0.60, P < 0.0001) and reduced haloperidol (quadratic equation; r2 = 0.67) were observed. Overall, the concentrations normalized for dose (C/D) of haloperidol were significantly different between the CYP2D6*1/*1, *1/*10 and*10/*10 genotype groups (one-way anova; P = 0.028). No significant differences between the genotype groups were found with respect to the C/D of reduced haloperidol (P = 0.755). However, in patients with daily doses less than 20 mg, significant differences in the C/D of haloperidol (P = 0.003), but not of reduced haloperidol, were found between the three major genotype groups. In patients with doses higher than 20 mg, no differences were found between the genotype groups for either haloperidol or reduced haloperidol. 68 patients (57%) used benztropine, an antimuscarinic agent. All four patients with a *5 allele (one together with *1 and three with *10) were found to use benztropine. The patients homozygous for the *1 allele seemed to need less benztropine than the patients with one or two mutated alleles (Fisher's exact test; P = 0.036). Conclusions, The dose-corrected steady state plasma concentrations of haloperidol, but not of reduced haloperidol, were significantly different between the CYP2D6*1/*1, *1/*10 and *10/*10 genotype groups when doses lower than 20 mg haloperidol were given. No differences were found at higher doses. These results suggest the involvement of CYP2D6 in the metabolism of haloperidol at low doses of haloperidol (< 20 mg daily), while another enzyme, probably CYP3A4, contributes at higher doses. [source]