Fig. 4: Explanation of DSSP output. Example: segment from Crambin. The two first columns contain the unique DSSP residue number and the corresponding PDB residue number. The third column (here empty) indicates the chain identifier if there are multiple chains. Then follows the amino acid ‘AA’ in one letter codes (note: lower case letters are all Cysteines, in order to mark Cysteine-bridges, e.g. residue 16 has a disulfide bond to residue 26). The ‘STRUCTURE’ section starts with the secondary structure synopsis (HBEGITS listed in order of priority in case of overlaps) and is followed by helix hydrogen bond indications for 310-,alpha-
and π-helix hydrogen bonds, where ‘>’ indicates
an acceptor, ‘<’ a donor and ‘X’ both. The bend and chirality
are each given a column followed by the b-bridge label columns
(lower case labels are parallel b-bridges and upper case are anti-parallel).
The DSSP numbers of their partners are written in the ‘BP1’
and ‘BP2’ columns. Each b-sheet is also given a label (independent of
the b-bridge labels) indicated in the adjacent column. The ‘ACC’
column contains the solvent accessible surface measured in Å2
by estimating the number of water molecules in contact with the present
residue. The two strongest backbone-backbone hydrogen bonds are then listed,
where ‘N-H-->O’ are donor hydrogen bonds and ‘O-->N-H’
acceptor hydrogen bonds. The format indicates the relative position of the
hydrogen bond partner followed by the energy in
DSSP number is 5 less than the present one and
that the hydrogen bond energy is –0.8
are all labelled: ‘TCO’ is cosine of the angle between the present C=O vector and
that of the previous residue (close to 1 for helices and –1 for sheets),
‘KAPPA’ is the bend angle
, ‘ALPHA’ is the
dihedral angle
<IMG SRC=){kind=small}
chirality ('+' when positive, '-’ when negative), finally the ‘PHI’,
‘PSI’ angles are given followed by the (x,y,z) Ca-coordinates.