FAQ

FAQs

1. Biological Background

1.1 What are odors?

1.2 What is a functional group?

1.3 How can odor be classified?

1.4 How are the mechanisms of action?

1.5 What physical and chemical characteristics of odors are there?

1.6 What is an InChi?

1.7 What is a SMILES?

1.8 What is a fingerprint?

2. Using SuperScent

2.1 What is "Scent Search"?

2.2 What is "Structure Search"?

2.3 What is "Scent Tree"?

2.4 What is "New Scent"?

2.5 What is the "Download Option"?


What are odors?

Odors are small chemical molecules which stimulate the sense of smell of humans and animals. They can be classified into two groups, pleasant or unpleasant smells. Pleasant odors are used in food and cosmetic industry, e.g. parfum. Stench are considered to be unpleasant and bear negative associations.

Top of Page


What is a functional group?

In organic chemistry, functional groups are specific groups of atoms which are responsible for characteristic chemical reactions of molecules. Chemical compounds which have the same functional group react in the same or similar way. These groups are divided into two parts due to the number of atoms:
with heteroatoms and without heteroatoms. Also they affect the chemical and physical characteristics of the whole molecule. The moities are parts of a molecule including substructures of functional groups.
For example, an ester functional group is divided into an alcohol and an acyl moiety.

Top of Page


How can odor be classified?

According to the stereo chemical theory of scents by Amoore there is a correlation between compound odor and the form of its molecule. That way globular molecules for example stimulate the fragrance of campher. Elongated molecules with cycle and chain induce a bloomy odor, whereas drop shaped elongated molecules have a minty scent. One of the most often used classification systems of Amoore for odors distinguishes between seven basic odors: camphor-like, musky, bloomy, menthol, essential, caustic and foul.1 Crocker and Henderson on the other hand support the assumption there only four classes: fragrant, acid, caprylic, burnt.2
Reference:
1Amoore,J.E. (1962a) The stereochemical theory of olfaction 1: Identification of the seven primary odours. Proceedings of the Scientific Section, Toilet Goods Association
2 Sherman Ross and A.E.Harriman,A preliminary study of the crocker-henderson odor-classification system, Bucknell Univerity

Top of Page


How are the mechanisms of action?

To sense a scent it is necessary that the substance-specific threshold is exceeded. However, too high concentrations of fragment substances lead to other scent qualities. If an odor molecule reaches the inside of the nose while breathing in if will stick to the olfactory epithelium. The olfactory cells are embeded in the mucosa nasi whereas their cell soma are in the mucosa. Their outgoing dendrites extent to the surface of the mucosa nasi. On the surface they are called cilia. Their membranes have suitable receptor proteins (ca. 1000) which are only sensitive to specific odor groups(log-key-principle). For each odor there are approximately 30,000 olfactory cells. The molecule sticks to one of the receptor-proteins so that a G-protein is released in the inside of this cell. With the help of the resulting electrical signal the information is passed on from the next higher level (glomeri olfactory) over the mitral cells to the brain. Through cooperation of the single odors a kind of model of a specific general impression emerges which indicates whether the scent is pleasant or unpleasant.

Top of Page


What physical and chemical characteristics of odors are there?

Physical characters of odors are:
- high surface activity
- low polarity
- poor water solubility
- high lipid solubility
- high vapour pressure
Determining for scent charcteristics is not the chemical reactivity but a poorly polar and a highly hydrophobic part of the molecule. The polar part is also called osmophoric group. Which consists of carbonyl-, ester-, hydroxyl-, or alcoxy-moieties as well as hetero aromatic analoges. Modifications of positions of functional groups or the allylsystem can lead to a loss of or modification of scents.

Top of Page


What is an InChi?

An InCHI ( IUPAC International Chemical Identifier) consists of characters which distinctly represent a chemical substance. It is designed in a way that a single compound produces always the same identifier. Therefore, IUPAC determines a nomenclature where InCHIs are created following three steps: Normalization; Canonicalization; Serialization.
There are six layers which are represented by an InCHI:
1. main layer
2. charge layer
3. stereochemical layer
4. isotopic layer
5. fixed-H-layer
6. reconnected layer


For more information about InCHIs:

http://wwmm.ch.cam.ac.uk/inchifaq/index.html#What%20is%20an%20InChi?

Top of Page


What is a SMILES?

SMILES (Simplified Molcular Input Line Entry System) is a chemical language with which atom and bond symbols can be represented by using the ASCII characters. It is a unique string that can be used as a universal identifier for a specific chemical structure with which molecules or reactions can be symbolized.

Top of Page


What is a fingerprint?

Fingerprints represent certain structural features of a molecule. There are two processes fingerprints are primarily used for:
similarity measures like calculations and screenings. Whereas calculation is a quantify of similarity of two molecules. However screening is a way of eliminating molecules as candidates in a substructure search. The fingerprint algorithm examines the molecule and generates patterns of the atom. The output is a string of bits and is added to the fingerprint.

Top of Page


What is "Scent Search"?

The Scent Seach gives an assortment of different types of queries. During the search 1347 compounds are screened. It is possible to search for only a name or the ID of a compound. Another alternative is to search for compounds which have a similar molweight or the same functional group. The result table shows the full information with synonyms, the producer, and the order information of compounds.

Top of Page


What is "Structure Search"?

In the Structure Search you can build your own structure or upload a structure file. When starting the similarity search a table of compounds with similar structures is presented.

Top of Page


What is "Scent Tree"?

The Scent Tree feature groups compounds which possess the same class. It is possible to choose one of the classification (e.g.fruity). The result table presents compounds which have the same class.

Top of Page


What is "New Scent"?

New Scent allows for uploading a new scent in the database. The process is divided into three steps,
first: upload the structure via load a file, draw this structure or fill out the SMILES or InChI windows.
secondly: you fill out the scent information window providing scent name, organism thirtly: you fill out the misc information window providing references and name of the user together with the e-mail address.

Top of Page


What is the "Download Option"?

With the download option you can retrieve the molfile for each molecule. The corresponding button download scent

can be found in the result table.

Top of Page