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Record W2401473574 · doi:10.1385/1-59259-182-5:155

Measuring DNA Demethylase Activity In Vitro

2003· article· en· W2401473574 on OpenAlexaff
Moshe Szyf, Sanjoy K. Bhattacharya

Bibliographic record

VenueHumana Press eBooks · 2003
Typearticle
Languageen
FieldBiochemistry, Genetics and Molecular Biology
TopicEpigenetics and DNA Methylation
Canadian institutionsMcGill University
FundersNational Cancer Institute
KeywordsDemethylationDNA demethylationCpG siteHpaIIDNADNA methylationMethylationCytosineBisulfiteRestriction enzymeBiochemistryMethylated DNA immunoprecipitationChemistryBisulfite sequencing5-MethylcytosineEnzymeMolecular biologyMethyltransferaseBiologyGeneGene expression

Abstract

fetched live from OpenAlex

The reaction catalyzing direct demethylation of DNA involves the removal of a methyl group residue from the 5′ position on cytosine; the products of the reaction are nonmethylated cytosine in the dinucleotide CpG and methanol (1). The study of the proteins involved in demethylation requires an assay for measuring enzymatic DNA demethylation. A number of assays were previously described for determining the state of methylation of CpG sequences DNA. For example, certain restriction enzymes such as HpaII or HhaI recognize subsets of CpG sequences only when the C is not methylated; thus, cleavage by this enzymes indicates demethylation of their recognition sequences (2) This assay is, however, obviously indirect and can only measure the state of methylation of a subset of CG sequences contained in the enzyme-specific recognition site. An additional problem is that this assay does not differentiate between DNA that is directly demethylated, and repair processes that remove methylated cytosines in DNA and replace them with other unmethylated cytosines found in the extracts. An additional assay is the bisulfite-mapping method, which can determine the state of methylation of cytosines at a single nucleotide resolution (3). This assay is based on the fact that nonmethylated cytosines are modified by bisulfite and converted to thymidine, whereas methylated cytosines are protected. This assay, similar to the restriction enzyme-based assays, is indirect; it does not measure demethylation but rather the conversion of cytosines.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.051
Threshold uncertainty score0.545

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.070
GPT teacher head0.273
Teacher spread0.203 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designBench or experimental
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations10
Published2003
Admission routes1
Has abstractyes

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