In article <3f0dvs$4eh at nof.abdn.ac.uk>, opt018 <opt018 at nof.abdn.ac.uk> wrote:
>Hao Xiao (haoxiao at cc.UManitoba.CA) wrote:
>: Four major forces are involved.
>>: London disperse forces: like moon (Ag) and earth (Ab), can not be too close
>>>: Hydrophorbic force: act like your ruber sticker on the glass wall. you squeeze
>>: Hydrogen and ionic bonding: act like your magnet sticker. Such forces
>-----
>>Nice explainations.
>>----
>>Question 1: Can London disperse force and Hydrophorbic force coexist in the same
>Ag/Ab complex pair?
Absolutely. In fact, generally speaking, all of these interactions are
involved in Ab/Ag binding.
>
>Question 2: You mentioned that you can increase the affinity by slightly
>increase the Ag size, simply because 'more water molecules are squeezed out'.
>Does this contradict the fact that Ab only recognize a certain fragment of Ag
>specifically, no matter how big the Ag size is?
>
Even within the region of recognition between Ab and Ag, there are only a few
specific sites of interaction. One can increase the size of the antigen by
adding functional groups to sites that fit within the antibody's binding
pocket, but which are not directly involved in the binding interaction.
As an example:
Pick up an item in your hand (any item). Although you can hold it securely,
not every bit of area of the item contacts your hand, and vice versa. Making
the antigen larger would be analagous to building up the item with putty until
it fits into your hand more exactly.
>Question 3: What is the forth major force? :-)
>
The hydrogen bond and ionic bond are generally considered to be different types
of interaction (they are not truly "forces" - the only "forces" are weak
nuclear, strong nuclear, gravitational, and electromagnetic. All of these
interatomic interactions are electromagnetic in nature). Ionic bonds occur
between two atoms or molecules that have discrete charges (i.e. ions), and
the atoms involved are very close together. Hydrogen bonds generally involve
at least one molecule that is formally neutral (but has a strong charge
polarization), and the interacting molecules are further apart. The bonds in
a salt crystal are ionic; the bonds between water molecules are hydrogen bonds.
BioKen
--
Ken Frauwirth (MiSTie #33025) _ _
frauwirt at mendel.berkeley.edu |_) * |/ (_ |\ |
Dept. of Molec. & Cell Bio. |_) | () |\ (_ | \|
Univ. of Cal., Berkeley Push the button...someone :(
