Methylophilus methylotrophus: A species of METHYLOPHILUS which is motile by single flagella. In addition to growth on methanol as a sole carbon source, growth also occurs on glucose. (From Bergey's Manual of Determinative Bacteriology, 9th ed)DNA Restriction-Modification Enzymes: Systems consisting of two enzymes, a modification methylase and a restriction endonuclease. They are closely related in their specificity and protect the DNA of a given bacterial species. The methylase adds methyl groups to adenine or cytosine residues in the same target sequence that constitutes the restriction enzyme binding site. The methylation renders the target site resistant to restriction, thereby protecting DNA against cleavage.Deoxyribonucleases, Type II Site-Specific: Enzyme systems containing a single subunit and requiring only magnesium for endonucleolytic activity. The corresponding modification methylases are separate enzymes. The systems recognize specific short DNA sequences and cleave either within, or at a short specific distance from, the recognition sequence to give specific double-stranded fragments with terminal 5'-phosphates. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 22.214.171.124.DNA-Cytosine Methylases: Methylases that are specific for CYTOSINE residues found on DNA.Methylophilus: A genus of straight or slightly curved gram-negative rods occurring singly or in pairs and isolated from sludge, mud, and river and pond water. (From Bergey's Manual of Determinative Bacteriology, 9th ed)DNA Cleavage: A reaction that severs one of the covalent sugar-phosphate linkages between NUCLEOTIDES that compose the sugar phosphate backbone of DNA. It is catalyzed enzymatically, chemically or by radiation. Cleavage may be exonucleolytic - removing the end nucleotide, or endonucleolytic - splitting the strand in two.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Gram-Negative Aerobic Bacteria: A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. This is because the cell walls of gram-negative bacteria are low in peptidoglycan and thus have low affinity for violet stain and high affinity for the pink dye safranine.Deoxyribonucleases, Type I Site-Specific: Enzyme systems containing three different subunits and requiring ATP, S-adenosylmethionine, and magnesium for endonucleolytic activity to give random double-stranded fragments with terminal 5'-phosphates. They function also as DNA-dependent ATPases and modification methylases, catalyzing the reactions of EC 126.96.36.199 and EC 188.8.131.52 with similar site-specificity. The systems recognize specific short DNA sequences and cleave at sites remote from the recognition sequence. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 184.108.40.206.S-Adenosylmethionine: Physiologic methyl radical donor involved in enzymatic transmethylation reactions and present in all living organisms. It possesses anti-inflammatory activity and has been used in treatment of chronic liver disease. (From Merck, 11th ed)5,10-Methylenetetrahydrofolate Reductase (FADH2): An FAD-dependent oxidoreductase found primarily in BACTERIA. It is specific for the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. This enzyme was formerly listed as EC 220.127.116.11 and 18.104.22.168.Methylenetetrahydrofolate Reductase (NADPH2): A flavoprotein amine oxidoreductase that catalyzes the reversible conversion of 5-methyltetrahydrofolate to 5,10-methylenetetrahydrofolate. This enzyme was formerly classified as EC 22.214.171.124.Oxidoreductases Acting on CH-NH Group Donors: Enzymes catalyzing the dehydrogenation of secondary amines, introducing a C=N double bond as the primary reaction. In some cases this is later hydrolyzed.5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase: An enzyme that catalyzes the formation of methionine by transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine. It requires a cobamide coenzyme. The enzyme can act on mono- or triglutamate derivatives. EC 126.96.36.199.Methylenetetrahydrofolate Dehydrogenase (NADP): An NADP-dependent oxidoreductase that catalyses the conversion of 5,10-methyleneterahydrofolate to 5,10-methenyl-tetrahydrofolate. In higher eukaryotes a trifunctional enzyme exists with additional METHENYLTETRAHYDROFOLATE CYCLOHYDROLASE and FORMATE-TETRAHYDROFOLATE LIGASE activity. The enzyme plays an important role in the synthesis of 5-methyltetrahydrofolate, the methyl donor for the VITAMIN B12-dependent remethylation of HOMOCYSTEINE to METHIONINE via METHIONINE SYNTHETASE.Methylenetetrahydrofolate Dehydrogenase (NAD+)Homocysteine: A thiol-containing amino acid formed by a demethylation of METHIONINE.Folic Acid: A member of the vitamin B family that stimulates the hematopoietic system. It is present in the liver and kidney and is found in mushrooms, spinach, yeast, green leaves, and grasses (POACEAE). Folic acid is used in the treatment and prevention of folate deficiencies and megaloblastic anemia.Vitamin B 12: A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.Methionine: A sulfur-containing essential L-amino acid that is important in many body functions.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Search Engine: Software used to locate data or information stored in machine-readable form locally or at a distance such as an INTERNET site.Quaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.Mallory Bodies: Cytoplasmic hyaline inclusions in HEPATOCYTES. They are associated with ALCOHOLIC STEATOHEPATITIS and non-alcoholic STEATOHEPATITIS, but are also present in benign and malignant hepatocellular neoplasms, and metabolic, toxic, and chronic cholestatic LIVER DISEASES.Chloride Peroxidase: An enzyme that catalyzes the chlorination of a range of organic molecules, forming stable carbon-chloride bonds. EC 188.8.131.52.Retroperitoneal Space: An area occupying the most posterior aspect of the ABDOMINAL CAVITY. It is bounded laterally by the borders of the quadratus lumborum muscles and extends from the DIAPHRAGM to the brim of the true PELVIS, where it continues as the pelvic extraperitoneal space.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.CobamidesFree Radicals: Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.Ammonium Sulfate: Sulfuric acid diammonium salt. It is used in CHEMICAL FRACTIONATION of proteins.Cations: Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.Ammonium Chloride: An acidifying agent that has expectorant and diuretic effects. Also used in etching and batteries and as a flux in electroplating.