Volume 2 Chapter 7 Numeric Sub-menu *CELA *CELB AND *CELC

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*CLASS is used to test for entries having a specified chemical class number or numbers.

CSD Contents

Following changes made in October 1997, there are now just 11 chemical class numbers:

Chemical Class Old Number(s) New Number
Carbohydrates 45 1
Nucleosides & nucleotides 47 2
Amino-acids, peptides and complexes 48, 82 3
Porphyrins, corrins & complexes 49 4
Antibiotics 50 5
Steroids 51 6
Terpenes 52-57 7
Alkaloids 58 8
Miscellaneous natural products 59 9
Supramolecular entities 60, 61 10
High polymers   11

An entry can be assigned up to four class numbers so, for example, a steroidal alkaloid would belong to class 6 and class 8.

Graphics QUEST3D Procedure

Select *CLASS from the NUMERIC sub-menu and respond to the standard numeric prompts.

Basic QUEST Procedure


T1 *CLAS .EQ. 8

This will register hits for all alkaloids, steroidal alkaloids, etc.

This is an ideal use of chemical class searching since alkaloids exhibit such a great variety of chemical connectivities.

Related Bit Screens

As a result of the changes made in October 1997:

Bit screen 136 (chemical classification field present) is no longer used.

Bit screen 57 (entry is an "organic" compound class 1-65 or 70) is now set to 1 if the compound does not contain any of TR, LN, AN, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi or Po.

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Volume 2 Chapter 7 Numeric Sub-menu *CODEN.