Olfaction enzymic

The a subunits and the Py complex have actions independent of those on adenylyl cyclase (see Figure 43-4 and Table 43-3). Some forms of tt stimulate channels and inhibit Ca channels, and some ttj molecules have the opposite effects. Members of the G, family activate the phospholipase C group of enzymes. The py complexes have been associated with channel stimulation and phospholipase C activation. G proteins are involved in many important biologic processes in addition to hormone action. Notable examples include olfaction (oColf) <1 vision (aj. Some examples are listed in Table 43-3. GPCRs are implicated in a number of diseases and are major targets for pharmaceutical agents. 

Dahl A. R. (1988) The effect of cytochrome P-450-dependent metabolism and other enzyme activities on olfaction. In Molecular Neurobiology of the Olfactory System, eds F. Margolis and T. Getchel, pp. 51-70. Plenum, New York. 

The mncns also contains cytochrome P450s, which are oxidative enzymes, and proteins known as odor-binding proteins. The odor-binding proteins belong to the family of lipocalins. The role in olfaction of these two classes of proteins is not certain. It is possible that they serve only to remove excess odorants and therefore contribnte to provision of the time dimension of olfaction, which is an important feature in survival. However, other roles have also been postnlated and wifi be discussed below. 

It has been observed that the discriminatory capabilities of human olfaction are tremendous It was estimated that an untrained person could differentiate up to ten million odors, perhaps even significantly more than that. Information theory then shows that in order to encode the qualities of ten million odors in a simple binary mode (Monoosmatic components on or off, their intensity, albeit important, is in this connection disregarded) only 2h to 27 specific profiles, disregarding possible and probable redundancies, and therefore the same number of complementary receptor sites would be required. Assuming furthermore that said redundancy, in which the informational modalities of two different specific receptor sites of two different olfactory neurons are confluent in one collector cell and therefore contribute to the expression of only one monoosmatic component is indeed operational it becomes necessary to increase the total number of types of specific receptor sites to 2k-30. This means that only 2U-30 specific detector proteins are required for structure recognition in the transduction process. This compares to about UOOO enzyme systems in different stages of activity estimated to be present in a cell any time. 

The next question arising is that about the minimum mmber of monoosmatic components required to encode an odor quality. It has been recognized by BEETS that an inherent "Principle of informational complexity" makes the perception of even a single odorant molecular species informationally complex, even if the odor information pattern is dominated by the terminal derivative (monoosmatic component) of a single chemoreceptory modality. But there has to be something like a minimum complexity still. In terms of the EMO there must be a minimum number of monoosmatic components essential to produce a minimal odor information pattern. Again, since this problem is not in the domain of peripheral processes, the Enzyme Model of Olfaction cannot provide an answer. However, experimental results obtained by POLAK (m) indicate that one... 

These results cannot be explained with any of the older theories of olfaction whereas the Enzyme Model of Olfaction not only can do that effortlessly, but actueLLly allows to predict these effects on the basis of generally accepted principles of molecular biochemistry. The concept of "STRUCTURE RECOGNITION AS PERIPHERAL PROCESS IN ODOR QUALITY CODING" represents only the special application of a more general mechanism of structvure recognition in peripheral processes to the problems of quality coding in olfac-r tion. 

Components of cedar wood such as cedrol (414) and cedrene shorten the sleeping time of mice. In order to search for a relationship between scent, olfaction, and detoxifying enzyme induction, (+)-cedrol (414) was administered to rabbits and dogs. From the metabolites from rabbits, two... 

Future olfactive (olfactive mucus) detection systems will probably be ultrasensitive chemical sensors [16] detecting nucleotides and hormones (e.g., pheromones). Biosensor research may also become orientated towards new bioreceptors [265], and perhaps even new biocatalysts, such as artificial enzymes [266]. 

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