Volume 2 Chapter 1 Build menu FASTQUEST

Back to Table of Contents

FUSE

Function

FUSE is used to join together two fragments, with the deletion of two atoms and one bond.

Examples

Ex. 1 Suppose the drawing area contains (i) - see below.

Ex. 2 Suppose the drawing area contains (i).

The above two examples illustrate how important it is to specify the atoms in the correct order. You should note that when the fused system is drawn then the position of residue 1 is not changed from its position prior to the FUSE operation, unless the resultant structure would not fit on the screen.

You should also note that normally the "fusion bond" in residue 1 determines the element type and bond type of the "fusion bond" after fusion has taken place. However, there is one situation where this is over-ridden - if the bond type of the second bond is aromatic. In this case the resultant bond will always be aromatic, and the following message will be issued after an alert:

Ex. 3 Suppose the drawing area contains (i) - see below.

Ex. 4 Although we normally regard fusion to involve the fusion of rings in fact the FUSE option can be generalised to the fusion of two bonds in non-ring residues.

Suppose the drawing area contains (iii).

You should note the following three error situations:

(a)
Suppose the drawing area contains:

(b)
Suppose the drawing area contains:

(c)
When you are prompted to select two atoms from a residue then the program expects that these atoms will be bonded to each other. If not, the resulting fused system may be disastrous! However, you can use UNDO to reverse the operation.

Note: In the FUSE operation any resultant overlapping atoms are eliminated.

For example, fuse:

then an atom is eliminated.

The easiest way to check for overlapping atoms is to select NUMBERS in the 2D-CONSTRAIN sub- menu.

Back to Table of Contents

Volume 2 Chapter 1 Build menu GRID.