Data Item _chem_comp.formula
Browse:
General 
- Item name
- _chem_comp.formula
- Category name
- chem_comp
- Attribute name
- formula
- Required in PDB entries
- Used in current PDB entries
- Yes, in about 100.0 % of entries
- Used in the Chemical Component dictionary
- Yes
Item Description
The formula for the chemical component. Formulae are written
according to the rules:
1. Only recognised element symbols may be used.
2. Each element symbol is followed by a 'count' number. A count
of '1' may be omitted.
3. A space or parenthesis must separate each element symbol and
its count, but in general parentheses are not used.
4. The order of elements depends on whether or not carbon is
present. If carbon is present, the order should be: C, then
H, then the other elements in alphabetical order of their
symbol. If carbon is not present, the elements are listed
purely in alphabetic order of their symbol. This is the
'Hill' system used by Chemical Abstracts.
Additional Descriptive Information for Depositors
The formula for the chemical component. Formulae are
written according to the rules:
1. Only recognised element symbols may be used.
2. Each element symbol is followed by a 'count'
number. A count of '1' may be omitted.
3. A space or parenthesis must separate each element
symbol and its count, but in general parentheses are
not used.
4. The order of elements depends on whether or not
carbon is present. If carbon is present, the order
should be: C, then H, then the other elements in
alphabetical order of their symbol. If carbon is not
present, the elements are listed purely in alphabetic
order of their symbol. This is the 'Hill' system used
by Chemical Abstracts.
Item Example
C18 H19 N7 O8 S
Data Type 
- Data type code
- text
- Data type detail
- text item types / multi-line text ...
- Primitive data type code
- char
- Regular expression
- [][ \n\t()_,.;:"&<>/\{}'`~!@#$%?+=*A-Za-z0-9|^-]*