Contacts of ligand ACE 1A in PDB entry 1I4E
Ligand-Protein Contacts (LPC) are derived
with the LPC software (Sobolev V., Sorokine A.,
Prilusky J., Abola E.E. and Edelman M. (1999) Automated
analysis of interatomic contacts in proteins.
Bioinformatics, 15, 327-332). A
short description of the analytical approach
is given at the end of the page.
On this page you will find:
- 3D ligand structure presentation with
Jmol, an open-source
Java viewer for chemical structures in 3D (top left window)
- Solvent accessible surface of the ligand
complexed with protein and in uncomplexed form
(top right window). Clicking
on "select" buttons highlights atoms in 3D picture
- List of residues in contact
with the ligand
- List of putative hydrogen
bonds formed by the ligand
- Full list of atomic contacts
formed by the ligand
- Values of ligand complementarity
(a function of atomic contact
surface area and the chemical properties of contacting atoms)
- Prediction of complementarity changes as a
function of atomic substitution
in the
ligand
Table II
Residues in contact with ligand ACE 1A
in PDB entry 1I4E (back to top of page)
Legend:
Dist - nearest distance (Å) between atoms of the ligand and the residue
Surf - contact surface area (Å2) between the ligand and the residue
HB - hydrophilic-hydrophilic contact (hydrogen bond)
Arom - aromatic-aromatic contact
Phob - hydrophobic-hydrophobic contact
DC - hydrophobic-hydrophilic contact (destabilizing contact)
+/- - indicates presence/absence of a specific contacts
* - indicates residues contacting ligand by their side chain
(including CA atoms)
----------------------------------------------------------
Specific contacts
---------------------------
Residue Dist Surf HB Arom Phob DC
----------------------------------------------------------
2A CYS* 1.3 61.7 + - - +
3A VAL 4.6 0.2 - - - +
87A ASP 2.4 28.5 - - - +
2317B HIS* 4.7 1.7 + - - +
2318B GLY 3.2 21.9 + - - +
2319B ASP* 3.0 31.4 - - + +
2324B TYR* 5.1 4.6 - - + -
2360B CYS* 4.4 0.9 - - + -
2362B GLY 3.8 13.5 - - - +
2363B ASP* 3.2 17.9 - - - +
----------------------------------------------------------
Table III
List of putative hydrogen bonds between ligand ACE 1A
and protein in PDB entry 1I4E
(back to top
of page)
Legend:
N - ligand atom number in PDB entry
Dist - distance (Å) between the ligand and protein atoms
Surf - contact surface area (Å2) between the ligand and protein atoms
------------------------------------------------------------------------
Ligand atom Protein atom
----------------- ---------------------------- Dist Surf
N Name Class Residue Name Class
------------------------------------------------------------------------
2 O II CYS 2A N III 2.2 0.9
2 O II GLY 2318B N III 4.6 1.4
2 O II HIS 2317B ND1 I 4.7 1.0
------------------------------------------------------------------------
Table IV
Full list of atomic contacts with ligand ACE 1A
in PDB entry 1I4E (back
to top of page)
Total number of contacts is 32
Legend:
N - ligand atom number in PDB entry
Dist - distance (A) between the ligand and protein atoms
Surf - contact surface area (A**2) between the ligand and protein atoms
* - indicates destabilizing contacts
------------------------------------------------------------------------
Ligand atom Protein atom
----------------- ---------------------------- Dist Surf
N Name Class Residue Name Class
------------------------------------------------------------------------
1 C VIII CYS 2A N III 1.3 44.0
1 C VIII CYS 2A CA VII 2.4 4.0
1 C VIII CYS 2A CB IV 3.2 0.7
1 C VIII ASP 87A O II 3.3 0.9*
1 C VIII CYS 2A SG VI 3.4 2.7
1 C VIII GLY 2318B O II 3.7 1.6*
1 C VIII ASP 87A C VI 4.2 0.2
1 C VIII CYS 2360B SG VI 4.4 0.4
1 C VIII TYR 2324B CE2 V 5.3 3.8
2 O II CYS 2A N III 2.2 0.9
2 O II ASP 87A O II 2.4 23.7*
2 O II CYS 2A CA VII 2.9 0.2
2 O II CYS 2A CB IV 3.2 1.4*
2 O II ASP 87A C VI 3.2 3.6
2 O II GLY 2318B O II 3.2 8.0*
2 O II CYS 2A SG VI 3.3 2.8
2 O II GLY 2318B N III 4.6 1.4
2 O II HIS 2317B ND1 I 4.7 1.0
2 O II HIS 2317B CB IV 4.8 0.7*
2 O II TYR 2324B CE2 V 5.1 0.5
3 CH3 IV CYS 2A N III 2.4 4.3*
3 CH3 IV ASP 2319B OD2 II 3.0 29.4*
3 CH3 IV ASP 2363B OD1 II 3.2 17.7*
3 CH3 IV GLY 2318B O II 3.5 11.0*
3 CH3 IV CYS 2A CA VII 3.5 0.9
3 CH3 IV ASP 2319B CG VI 3.7 1.8
3 CH3 IV GLY 2362B O II 3.8 13.5*
3 CH3 IV ASP 2319B CB IV 4.1 0.2
3 CH3 IV ASP 2363B CG VI 4.3 0.2
3 CH3 IV VAL 3A N III 4.6 0.2*
3 CH3 IV CYS 2360B CB IV 4.7 0.4
3 CH3 IV TYR 2324B CE2 V 5.5 0.2
------------------------------------------------------------------------
Table V
Complementarity values for the ligand ACE 1A
in PDB entry 1I4E (back to top of page)
---------------------------------------------
Theoretical maximum (Å2) 178
Actual value (Å2) -42
Normalised complementarity -0.24
---------------------------------------------
Table VI
Normalised complementarity as a function of atomic
substitution for ligand ACE 1A
in PDB entry 1I4E (back
to top of page)
Legend:
| N | - ligand atom number in PDB entry |
| Bold
| - indicates atomic
substitution which could stabilize the complex |
| Italics | - indicates atomic
substitution which could destabilize the complex |
|
Ligand atom | Atom class |
|---|
| N | Type | Class | I
| II | III | IV | V |
VI | VII | VIII |
|---|
| 1 | C
| VIII |
-0.22 |
-0.24
|
-0.75 |
-0.73
|
-0.21 |
-0.21
|
-0.75 |
-0.24
|
| 2 | O
| II |
0.12 |
-0.24
|
0.09 |
-0.25
|
0.14 |
0.14
|
0.11 |
-0.21
|
| 3 | CH3
| IV |
0.61 |
-0.19
|
0.55 |
-0.24
|
0.61 |
0.61
|
0.55 |
-0.19
|
A short description of the
analytical approach (back to top of page)
The analysis of ligand-protein contacts used in this page
is based upon the surface complementarity approach
developed in:
Sobolev V., Wade R.C., Vriend G.
and Edelman M. PROTEINS (1996)
25, 120-129.
The complementarity function
therein is defined as:
Where Sl is the sum of all
surface areas of legitimate atomic contacts between
ligand and receptor, Si is the sum of
all surface areas of illegitimate atomic
contacts, and E is a repulsion term.
Legitimacy depends on the hydrophobic-hydrophilic
properties of the contacting atoms. In order to
define it, for each inter-atomic contact,
eight atom classes have been introduced:
I Hydrophilic - N and O that can donate and accept hydrogen bonds
(e.g., oxygen of hydroxyl group of Ser. or Thr)
II Acceptor - N or O that can only accept a hydrogen bond
III Donor - N that can only donate a hydrogen bond
IV Hydrophobic - Cl, Br, I and all C atoms that are not in
aromatic rings and do not have a covalent bond to
a N or O atom
V Aromatic - C in aromatic rings irrespective of any other
bonds formed by the atom
VI Neutral - C atoms that have a covalent bond to at least one
atom of class I or two or more atoms from class II
or III; atoms; S, F, P, and metal atoms in all cases
VII Neutral-donor - C atoms that have a covalent bond with only one
atom of class III
VIII Neutral-acceptor - C atoms that have a covalent bond with only
one atom of class II
For each pair of contacts the state of legitimacy
is shown below:
Legend:
+, legitimate
-, illegitimate
------------------------------------------------------------
Atomic class I II III IV V VI VII VIII
------------------------------------------------------------
I (Hydrophilic) + + + - + + + +
II (Acceptor) + - + - + + + -
III (Donor) + + - - + + - +
IV (Hydrophobic) - - - + + + + +
V (Aromatic) + + + + + + + +
VI (Neutral) + + + + + + + +
VII (Neutral-donor) + + - + + + - +
VIII (Neutral-acceptor) + - + + + + + -
------------------------------------------------------------
WARNING !!
Atom classes for ligands are automatically
assigned based on the atomic coordinates. However, in
three cases the automatic assignment is
currently ambiguous (due to low resolution). In these
three cases, the user is advised to manually analyze
the full list of contacts (Table IV).
1. Carbon atoms belonging to a 4-, 5- or 6-member ring are
considered "aromatic" (Class V) if the ring is approximately
planar, and "hydrophobic" (Class IV) or "neutral" (Classes
VI, VII, VIII) if the ring is non-planar.
2. The oxygen atom of a carbonyl or hydroxy group is considered
"hydroxy" (Class I) if the CO bond is longer than 1.29 Å, and
"carbonyl" (Class II) if shorter.
3. All nitrogen atoms are considered "hydrophilic" (Class I).
IN YOUR STRUCTURE, the following atoms
fall in these ambiguous cases:
Ligand ACE 1
2. Oxygen ("hydroxy" or "carbonyl")
2 O
Please E-mail any questions and/or suggestions
concerning this page to
Vladimir.Sobolev@weizmann.ac.il