Odor enzyme role

Alternative second-messenger pathways may be at work in olfactory transduction. The role of cAMP in olfactory transduction is well established. Are there alternative pathways, such as those involving phospholipids and Ca2+ Several groups have reported that certain odorants can elicit an increase in the phosphoinositde second messenger inositol 1,4,5,-trisphosphate (IP3) (Ch. 20). However, there is no clear evidence that IP3 directly mediates an electrical response in OSNs, nor is there a clear rationale for two parallel excitatory odor transduction cascades. However, more recent data support the idea that phos-phoinositides or enzymes related to their metabolism may play a modulatory role, shaping the OSN output by... 

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. 

The most obvious role for oxidative enzymes in the olfactory mucosa would be removal of excess or spent signal material. However, some evidence suggests that products of cytochrome oxidation are detected by the olfactory receptors and thus constitute a part of odor perception (36). 

The definition of oxidized fish oil-like aromas still leave fresh fish aromas undefined. Various freshly harvested fish have distinguishing aromas, but they also are characterized by a common plant-like, seaweed-like aroma. Thus, compounds and reaction pathways different from random autoxidation appear likely and reasonable. Even conflicting descriptions of fishy odors, i.e., including roles for volatile amines (2 19) and sulfur compounds (20-22), can be accommodated by the hypothesis that previously unrecognized biochemical reactions yield characterizing fresh fish aromas. These premises led to investigations (23-26) which have resulted in the identification of a group of enzymically-derived volatile aroma compounds that contribute fresh, plant-like aromas to freshly harvested fish (Table I). 

W. S. Leal, Odorant reception in insects Roles of receptors, binding proteins, and degrading enzymes. Annual Review of Entomology, 58 373-391, 2013. 

The science and technology required for the preparation of microcapsules from different natural and synthetic polymeric materials has made rapid progress. They are being used in various fields for their ability to solidify liquids to isolate reactive compounds to remove color, odor, and toxicity as well as to regulate and control the release of included compounds. The immobilization of enzymes and the development of polymeric drugs are also playing an important role. 

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