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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> De Novo Synthesis Deiodination
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dbSTS
A subsidiary sequence database used to store sequence tagged sites (STSs).
DCC gene
See deleted in colon cancer gene.
Dcm methylation
Methylation of internal cytosine residues to 5-methylcytosine by DNA cytosine methylase (Dcm) in the sequence CCWGG in E.coli.
ddNTP
See dideoxynucleotide.
de novo methylase
Enzymes that add methyl groups to unmethylated DNA at specific genes.
de novo pathway
(L. from the beginning anew) The pathway for the synthesis of a biomolecule from simple precursors. For eg. de novo pathway for purine synthesis.
de novo synthesis
The formation of an essential molecule from simple precursor molecules.
Deaminase
An enzyme that removes amino groups from molecules.
Deamination
The removal of amino groups from amino acids or nucleotides.
Death phase
The final growth phase, during which nutrients are depleted and cell number decreases. See growth phases.
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Death receptor pathway
An apoptotic pathway in which death receptors such as Fas transduce the death signal to caspases which execute the cell death programme.
Debranching enzyme
A polypeptide with two enzyme activities that removes the branches in the glycogen molecule during glycogenolysis. In the first step, a[1→4]→a[1→4] Glucan transferase (glycosyl transferase) transfers a trisaccharide unit from one branch to the chain terminus of another branch, exposing the 1→6 branch point. In the next step, amylo[1,6]-glucosidase hydrolyses the 1→6 linkage.
Debridement
Removal of necrotic or infected tissue or foreign material from a wound.
Decarboxylation
Removal of a carboxyl (-COOH) group from a compound.
Deceleration phase
The phase of declining growth rate that follows the linear phase and precedes the stationary phase in most batch-suspension cultures.
Decline phase
See death phase
Deconvolution
Mathematical procedure used to separate the overlapping effects of molecules such as mixtures of compounds in a high-throughput screen, or mixtures of cDNAs in a high density array.
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Dedifferentiation
The process by which cells lose specialisation of function and undergo cell division to form a mass of cells. These cells may subsequently differentiate again to form either the same cell type or a different one in response to appropriate stimuli (such as wounding and in tissue cultures). See redifferentiation.
Default pathway
A constitutive secretory pathway that automatically delivers material from the Golgi apparatus to the plasma membrane if there is no other sorting signal available.
Defective virus
A virus that lacks an essential genetic information and therefore unable to reproduce. Such viruses can be propagated in a host cell by a helper virus that provides the missing function.
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Defensins
Peptides produced by different organisms that form part of the innate host defence system against invading microorganisms. These have a broad spectrum of activity against bacteria, fungi, and some viruses. They are found in high concentration in the phagocytic white blood cells of mammals and birds as well as in the intestine and skin. They insert into the members of the microbes and destroy them.
Deficiency
Insufficiency or absence of one or more usable forms of enzymatic, nutritional or environmental requirements that can impair growth, development and other physiological functions.
Defined
1. Fixed conditions of medium, environment and protocol required for growth. 2. Elements of a tissue culture medium that are precisely known. See undefined.
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Degeneracy
Refers to the lack of an effect of changes in the third base of the codon on the amino acid that is represented. The existence of more than one codon for most of the amino acids (synonyms codons).
It arises from the redundancy that results from 64 triplets in a triplet code that encodes only 20 amino acids.
Degenerate code
Refers to the existence of more than one codon for specifying a single amino acid in the genetic code.
Degenerate primers
A mixture of PCT primers of similar sequence but with variations at one or more positions. These are used for purposes such as deduction of primer sequences from amino acids sequences, to search for homologous genes between species and to search for novel members of a known family of genes.
Degeneration
1. Changes that occur in cells, tissues or organs as a result of disease 2. The reduction in size or complete loss of organs during evolution.
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Degradation
The process by which substances are broke down. In a degradative pathway, larger molecules are enzymatically cleaved to form small molecules.
Degradation condensation reaction
The joining of two molecules coupled to the removal of a molecule of water.
Degradative plasmids
Plasmids that encode enzymes that breakdown substrates such as lactose, toluene or citrate.
Degradome
The entire protease complement of human cells and tissues.
Degradomics
The application of genomic and proteomic approached to identify the protease and protease-substrate repertories, or degradomes, on an organism-wide scale. This are of study will reveal new roles for proteases in vivo that will enable the identification of new pharmaceutical targets to treat disease.
Degrees of freedom
The number of independent variables in an experiment,
Dehalogenation
The removal of halogens (chlorine, iodine, bromine, fluorine) from molecules during biodegradation.
Dehydroepiandrosterone (DHEA)
The major androgen produced by the adrenal cortex. Most of the DHEA is converted to its sulphate. DHEA is acted upon by 3β-hydroxysteroid dehydrogenase and D5.4 isomerase to form the more potent androstenedione, which is reduced at the C17 position to form testosterone, the most potent adernal androgen. Thus, DHEA functions as a prohormone.
Dehydrogenase An enzyme that catalyses removal of hydrogen from substrates.
Dehydrogenation The process by which hydrogen ions are removed from ab organic molecule by dehydrogenases. Also called oxidation.
Deiodinase A microsomal NADPH-dependent enzyme that accomplishes deiodination of MIT and DIT during thyroglobulin hydrolysis with reutilization of the liberated iodine.
Deiodination The major pathway of thyroid hormone inactivation. Two distinct iodothyronine deiodinases accomplish the monodeiodination of the outer phenolic or the inner tyrosyl ring to yield T3 and reverse T3 (rT3) respectively. Deiodination results in the activation of T4 and T3, the biologically active form.
Deionised water Water from which most inorganic (except Na) and most organic compounds are removed.
Delayed type hypersensitivity (DTH) A T cell-mediated reaction to antigen, that involves release of lymphokines and recruitment of monocytes and macrophages. It requires 24-48 hours to develop this response completely.
Deleted in colon cancer (DCC) gene
A gene located on chromosome 18q that has a role in cell adhesion. Mutations of the DCC gene are common in colorectal cancers.
Deletion
A change in DNA brought about by the removal of one or more bases.
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