Biomaterial Database

Methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase from porcine liver. Location of the activities in two domains of the multifunctional polypeptide. 1979

L U Tan, and R E MacKenzie

Chymotryptic cleavage of the trifunctional protein methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase from pig liver yields a fragment of two-thirds the original polypeptide that retains only synthetase activity. A smaller polypeptide corresponding to about one-third of the original polypeptide was shown earlier to retain dehydrogenase-cyclohydrolase activity. On immunodiffusion, the synthetase fragment cross-reacts and shows partial identity with antibodies raised against the uncleaved enzyme but shows nonidentity with the dehydrogenase-cyclohydrolase fragment, suggesting that the two fragments are derived from different regions of the polypeptide. Amino-terminal analysis of the peptides and uncleaved enzyme indicate that the dehydrogenase-cyclohydrolase activities are located at the amino-terminal region and the synthetase near the carboxyl-terminal portion of the polypeptide.

UI	MeSH Term	Description	Entries
D008025	Ligases	A class of enzymes that catalyze the formation of a bond between two substrate molecules, coupled with the hydrolysis of a pyrophosphate bond in ATP or a similar energy donor. (Dorland, 28th ed) EC 6.	Ligase,Synthetases,Synthetase
D008754	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 (NADP+),Methylenetetrahydrofolate Dehydrogenase,Dehydrogenase, Methylenetetrahydrofolate
D009097	Multienzyme Complexes	Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.	Complexes, Multienzyme
D010088	Oxidoreductases	The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)	Dehydrogenases,Oxidases,Oxidoreductase,Reductases,Dehydrogenase,Oxidase,Reductase
D005574	Formate-Tetrahydrofolate Ligase	A carbon-nitrogen ligase that catalyzes the formation of 10-formyltetrahydrofolate from formate and tetrahydrofolate in the presence of ATP. In higher eukaryotes the enzyme also contains METHYLENETETRAHYDROFOLATE DEHYDROGENASE (NADP+) and METHENYLTETRAHYDROFOLATE CYCLOHYDROLASE activity.	Tetrahydrofolate Formylase,Formyltetrahydrofolate Synthetase,Formate Tetrahydrofolate Ligase,Formylase, Tetrahydrofolate,Ligase, Formate-Tetrahydrofolate,Synthetase, Formyltetrahydrofolate
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000619	Aminohydrolases
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013763	Tetrahydrofolates	Compounds based on 5,6,7,8-tetrahydrofolate.