olefin (C=C):
any organic molecule containing a carbon to carbon double bond.
organelle:
a subcellular unit; a structure within a cell with a specialized
function. Examples are: mitochondria, centrioles, Golgi apparati,
tubules, endoplasmic reticulum, plastids, lysosomes, fibrils.
ornithine (NH2-CH2-CH2-CH2-CHNH2-COOH):
an amino acid possessing a 3 carbon side with a terminal amino group;
a component of the urea cycle produced from arginine by arginase;
a precursor to putrescine by action of ornithine decarboxylase.
ornithine decarboxylase (ODC):
an enzyme which releases a carboxyl group
from the amino acid ornithine to produce putrescine a polyamine and
precursor to other polyamines. ODC is induced along with other polyamine
producing enzymes just before and during mitosis. ODC can be reversibly
inhibited by oxidation of one of its thiol groups.
orthoquinone:
a compound composed of an aromatic ring and two adjacent
carbonyl groups. Orthoquinones can be produced by dehydrogenation of
the enediol group of any analogue of catachol. Many naturally occuring
polyphenols such as the flavone esters of gallic acid can be readily
oxidized to orthoquinones (also known as tannins) giving them bitter
tasting, astringent, and antibiotic properties. Injury to plant tissues
activates enzymes such as laccase or peroxidase which rapidly converts
polyphenols into tannins. These have an astringent effect which
mechanically protects the plant. Oxidized tannins react with amines to
produce the brown color change observed on bruised fruit. Tannins also
protect plants due to their known broad spectrum antibacterial effects.
oxidant [O]:
a contraction of the words oxidizing agent; any substance which
accepts electron(s); any substance which abstracts hydrogen or electron(s);
that reactant which receives electrons or hydrogen atoms. Examples are:
the positively charged anodic plate; hydronium cation; metal cations;
quinones; glyoxals; imines; various compounds of oxygen; halogens;
disulfides.
oxidase:
an enzyme which catalyses the removal of electrons from some substrate
and passes them on to oxygen (O2). This produces superoxide (*OO-).
oxidation:
the process of losing electrons or hydrogen atoms. This can occur
by various means: abstraction by an acceptor (an oxidant); removal by
a positively charged plate (an anode); or scattering by collision with
a high energy particle.
oxidative deamination:
a two part process in which two hydrogen atoms are
first abstracted (one from an amino group and one from an adjacent carbon
atom) producing an imine, which secondarily hydrolyses to release a
molecule of ammonia plus a carbonyl compound (usually an aldehyde).
oxidative therapy:
any method of treating illness using oxidants; promoting,
accelerating, or supplementing the normal physiologic oxidative processes
in the body.
oxidize:
the process of taking up or accepting electrons; to abstract
electrons or hydrogen atoms; to draw out electrons from an element
by the addition of oxygen or a halogen.
oxido-reductase:
any enzyme which catalyses the transfer of reducing
equivalents (electrons or hydrogen atoms) from a donor substrate
(the reductant) to a receptor substrate (the oxidant). Oxido-reductases
utilize redox active thiol groups as electron/hydrogen shuttles, or
various prosthetic groups and cofactors which can be reversibly reduced
and oxidized. Common cofactors are: PQQ, NAD, FAD, CoQ, iron, and copper.
oxidosis:
the condition of abnormal or excessive levels of oxidants in a
biologic fluid. Oxidosis can result from a deficiency of reductant
supply, from any deactivation of reductants, from the introduction
of excessive doses of oxidants, or from the generation of
oxyradicals. The extent of oxidosis is quantifiable by an electrode
and a volt meter.
oxo group (X=O):
a reactive group which is composed of one atom of oxygen
covalently bound by a double bond to another atom usually carbon.
oxygen (O or O2):
the element named after its characteristic to oxidize;
the element which produces or causes ("gen") biting ("oxy").
oxygenase:
any enzyme which catalyses the addition of oxygen atom(s) to the
substrate.
oxygenation:
the physiologic process of delivering diatomic oxygen to a
bodily fluid or tissue.
oxyhemoglobin:
the product of attachment of diatomic oxygen to the iron atoms of
the heme groups in hemoglobin in the red blood cells. Oxyhemoglobin
carries oxygen to peripheral tissues via the circulatory system.
The release of oxygen is modulated by the level of
2,3 diphosphoglycerate present in the RBC's.
oxyradical (RO*):
any free radical possessing an unpaired electron situated
at an oxygen atom; an oxygen centered free radical. Examples are:
hydroxyl (HO*), alkoxyl (RO*), phenoxyl (ArO*), hydroperoxyl (HOO*), and
alkylperoxyl (ROO*). Most oxyradicals are rapidly and highly reactive
molecular species which readily add to pi bonds or abstract hydrogen
atoms. They can readily be quenched by numerous reducing agents.
ozone (O3):
triatomic oxygen; a highly reactive strongly oxidizing gas
composed of three atoms of oxygen. Ozone is usually produced by a physical
energy source such as an electric spark or ultraviolet C which breaks
apart diatomic oxygen to release atoms of monoatomic oxygen which
rapidly add to other molecules of diatomic oxygen. Ozone is unstable and
gradually recombines to revert to the stable diatomic oxygen. Ozone
deodorizes, bleaches and disinfects. Ozonation of blood followed by
immediate reinfusion has demonstrated numerous therapeutic benefits being
antiallergic, antibiotic, and antineoplastic.
ozonide (RO3R'):
the product of the addition of one molecule of ozone to
an olefin. In concentrated form ozonides are explosive. They react rapidly
with water to produce two aldehydes plus hydrogen peroxide.
