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Gonyautoxin
Gonyautoxins (GTX) are a few similar toxic molecules that are naturally produced by algae. They are part of the group of saxitoxins, a large group of neurotoxins along with a molecule that is also referred to as saxitoxin (STX), neosaxitoxin (NSTX) and decarbamoylsaxitoxin (dcSTX). Currently eight molecules are assigned to the group of gonyautoxins, known as gonyautoxin 1 (GTX-1) to gonyautoxin 8 (GTX-8). Ingestion of gonyautoxins through consumption of mollusks contaminated by toxic algae can cause a human illness called paralytic shellfish poisoning (PSP). Natural sources Gonyautoxins are naturally produced by several marine dinoflagellates species (''Alexandrium'' sp., ''Gonyaulax'' sp., '' Protogonyaulax'' sp.). The paralytic shellfish poisoning caused by these toxins is connected with dinoflagellate blooms known as “red tides”, even though the coloration of the water isn’t a necessity. The threshold concentration of the organisms that are capable to produce the toxins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decarbamoylsaxitoxin
Decarbamoylsaxitoxin, abbreviated as dcSTX, is a neurotoxin which is naturally produced in dinoflagellate. DcSTX is one of the many analogues of saxitoxin (STX). Saxitoxin is a tricyclic alkaloid compound, which has multiple structural related neurotoxins. One of those related neurotoxins is neosaxitoxin (NSTX) in which the nitrogen at position 2 is not bound to a hydrogen, but to a hydroxyl group. Another toxic analogue of saxitoxin is gonyautoxin (GTX). The difference between GTX and STX is that on the carbon at position 11, a hydrogensulfate is bound. Between dcSTX, NSTX and GTX, dcSTX is the one which varies most from saxitoxin. In dcSTX there is a double bond between carbons 2 and 3, while there is a single bond in STX. This also results in that the double-bonded N to carbon number 3 in STX, is a single bound NH2 in dcSTX. Another difference between decarbamoylsaxitoxin and saxitoxin is that the amino-carbonyl-oxy-methyl group at position 1 in STX, is only a CH2OH group in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxins
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations across the cell membrane, or c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase II Metabolism
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug or poison. These pathways are a form of biotransformation present in all major groups of organisms and are considered to be of ancient origin. These reactions often act to detoxify poisonous compounds (although in some cases the intermediates in xenobiotic metabolism can themselves cause toxic effects). The study of drug metabolism is called pharmacokinetics. The metabolism of pharmaceutical drugs is an important aspect of pharmacology and medicine. For example, the rate of metabolism determines the duration and intensity of a drug's pharmacologic action. Drug metabolism also affects mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizing
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bonds ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase I Metabolism
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug or poison. These pathways are a form of biotransformation present in all major groups of organisms and are considered to be of ancient origin. These reactions often act to detoxify poisonous compounds (although in some cases the intermediates in xenobiotic metabolism can themselves cause toxic effects). The study of drug metabolism is called pharmacokinetics. The metabolism of pharmaceutical drugs is an important aspect of pharmacology and medicine. For example, the rate of metabolism determines the duration and intensity of a drug's pharmacologic action. Drug metabolism also affec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotransformation
Biotransformation is the biochemical modification of one chemical compound or a mixture of chemical compounds. Biotransformations can be conducted with whole cells, their lysates, or purified enzymes. Increasingly, biotransformations are effected with purified enzymes. Major industries and life-saving technologies depend on biotransformations. Advantages and disadvantages Compared to the conventional production of chemicals, biotransformations are often attractive because their selectivities can be high, limiting the coproduction of undesirable coproducts. Generally operating under mild temperatures and pressures in aqueous solutions, many biotransformations are "green". The catalysts, i.e. the enzymes, are amenable to improvement by genetic manipulation. Biotechnology usually is restrained by substrate scope. Petrochemicals for example are often not amenable to biotransformations, especially on the scale required for some applications, e.g. fuels. Biotransformations can be s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapse
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to the transmission of nervous impulses from one neuron to another. Neurons are specialized to pass signals to individual target cells, and synapses are the means by which they do so. At a synapse, the plasma membrane of the signal-passing neuron (the ''presynaptic'' neuron) comes into close apposition with the membrane of the target (''postsynaptic'') cell. Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process. In many synapses, the presynaptic part is located on an axon and the postsynaptic part is located on a dendrite or soma. Astrocytes also exchange information with the synaptic neurons, responding to synaptic activity and, in turn, regulating neurotransmission. Syna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postsynaptic Membrane
Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie perception and thought. They allow the nervous system to connect to and control other systems of the body. At a chemical synapse, one neuron releases neurotransmitter molecules into a small space (the synaptic cleft) that is adjacent to another neuron. The neurotransmitters are contained within small sacs called synaptic vesicles, and are released into the synaptic cleft by exocytosis. These molecules then bind to neurotransmitter receptors on the postsynaptic cell. Finally, the neurotransmitters are cleared from the synapse through one of several potential mechanisms including enzymatic degradation or re-uptake by specific transporters either on the presynaptic cell or on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Channels
Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the channel for such ions, i.e. either a voltage-change ("voltage-gated", "voltage-sensitive", or "voltage-dependent" sodium channel; also called "VGSCs" or "Nav channel") or a binding of a substance (a ligand) to the channel (ligand-gated sodium channels). In excitable cells such as neurons, myocytes, and certain types of glia, sodium channels are responsible for the rising phase of action potentials. These channels go through three different states called resting, active and inactive states. Even though the resting and inactive states would not allow the ions to flow through the channels the difference exists with respect to their structural conformation. Selectivity Sodium channels are highly selective for the transport of ions across cell membr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nervous System
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or '' efferent'' nerves, while those nerves that transmit information from the body to the CNS are called sensory nerves or '' afferent''. Spinal nerves are mixed nerves that serve both fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
