Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
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Target Concepts:
Gene/Protein
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Query: EC:3.1.26.4 (
RNase H
)
2,751
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Two ribonucleases H (RNases H) were purified to apparent homogeneity from the yeast Saccharomyces cerevisiae. The enzymes were separated from the previously described yeast ribonuclease H (
RNase H
(70), Karwan, R., Blutsch, H., and Wintersberger, U. (1983) Biochemistry 22, 5500-5507) by chromatography on Mono Q and blue-Sepharose columns and from each other on a Mono S column. The two proteins,
RNase H
(55) of molecular weight around 55,000 and
RNase H
(42) of molecular weight around 42,000, exhibit distinct enzymatic properties:
RNase H
(55) acts as a 5'-exonuclease of low specific activity and produces predominantly monoribonucleotides from the synthetic hybrid poly(rA)-poly(dT).
RNase H
(42) efficiently releases oligoribonucleotides from the same substrate. Polyclonal antibodies against these proteins do not cross-react with
RNase H
(70), and thus, these two RNases H probably do not represent proteolytic breakdown products of
RNase H
(70). Peptide maps obtained by total digestion of
RNase H
(55) and
RNase H
(42) with
trypsin
reveal several common peptides and, therefore, suggest that the two enzymes are related to each other. We tentatively conclude that
RNase H
(55) is proteolytically processed to
RNase H
(42) in vivo.
...
PMID:In addition to RNase H(70) two other proteins of Saccharomyces cerevisiae exhibit ribonuclease H activity. 304 96
Partially purified
ribonuclease H
from rat liver nuclei can be inactivated by a soluble fraction from rat intestine; this inactivation is restored by adding trypsin inhibitor, suggesting that the factor is a protease. A preparation has been isolated and purified to homogeneity. The molecular weight of the enzyme was estimated as 28 000 with an optimum pH of 8.0 and an isoelectric point at pH 4.5--4.7. The inactivating and proteolytic activities were observed in parallel throughout the purification procedures. Diisopropylphosphorofluoridate inhibited the protease activity. The protease inactivates deoxyribonuclease I, pyruvate kinase, and aldolase. From experiments with protease modifiers, it seems to be a serine protease of a
trypsin
-like nature.
...
PMID:A protease from rat intestine. 624 51
An endogenous nuclear enzyme,
RNase H
, is an important component in determining the efficacy of antisense oligodeoxynucleotides (ODNs). In an effort to improve the potency of antisense ODNs, conjugates with three different nuclear targeting signal peptides were prepared. These short peptide sequences have been shown to facilitate transport of macromolecules into the nucleus of cells. Efficient chemistry for the synthesis of ODN-peptide conjugates is described. Reaction of 5'-aminohexyl-modified ODNs with iodoacetic anhydride gave pure iodoacetamide ODNs (IA-ODNs) in good yield. These electrophilic intermediates were reacted with thiol-containing peptides to give ODN-peptides in excellent yield and purity. The ODN-peptides were further characterized by proteolysis with
trypsin
. Thermal denaturation studies with ssDNA targets showed little effect of the 5'-peptide modifications on the hybridization properties of the ODN. The effect of the nuclear signal peptides on antisense potency was evaluated in the freshwater ciliate Paramecium. A 3'-hexanol-modified 24-mer antisense ODN, complementary to the mRNA for calmodulin, alters regulation of membrane ion channels and swimming behavior of these cells. A 2'-O-methyl analog of this ODN was inactive, thus providing evidence that this activity in Paramecium is mediated by
RNase H
. Antisense ODN-nuclear signal peptide conjugates were transfected into the cells by electroporation. Surprisingly, these conjugates showed no antisense effects in comparison to a 5'-unmodified control ODN. Random peptides or amino acids conjugated to the 5'-terminus did not decrease antisense activity.
...
PMID:Synthesis and evaluation of nuclear targeting peptide-antisense oligodeoxynucleotide conjugates. 771 Oct 95
