What chemical / physical bonds bind adrenaline to its receptor site?

Answer 1

The adrenergic receptors (or adrenoceptors) are a class of G protein-coupled receptors that are targets of the catecholamines. Adrenergic receptors specifically bind their endogenous ligands, the catecholamines adrenaline and noradrenaline (also called epinephrine and norepinephrine in the USA), and are activated by these.

Many cells possess these receptors, and the binding of an agonist will generally cause the cell to respond in a fight-or-flight manner. For instance, the heart rate will increase and the pupils will dilate, energy will be mobilized, and blood flow diverted from other organs to skeletal muscle.

There are several types of adrenergic receptors, but there are two main groups: α-Adrenergic and β-Adrenergic.

* α receptors bind norepinephrine and epinephrine, though norepinephrine has higher affinity. Phenylephrine is a selective agonist of the α receptor.
* β receptors are linked to Gs proteins, which in turn are linked to adenylyl cyclase. Agonist binding thus causes a rise in the intracellular concentration of the second messenger cAMP. Downstream effectors of cAMP include cAMP-dependent protein kinase (PKA), which mediates some of the intracellular events following hormone binding.

Answer 2

Adrenaline uses a variety of structural motifs in order to bind effectively. These include:

1. Hydrophobic interactions using the catechol ring system
2. Hydrogen bonding via a hydroxyl group
3. Ionic bonding using the terminal amino group (it is protonated at physiological pH and thus ionic bonding to a negatvely charged amino acid side chain on the receptor is possible).

A further point is that the carbon to which the hydroxyl group is attached is a stereocentre, and thus only one enantiomer of adrenaline will bind effectively to the receptor.

Answer 3

Not sure. It's been a while since any real physiology. Its not Hydrophobic interactions. van der waals may assist but too weak by themselves so either ionic or hydrogen bonding. Adrenaline (epinephrine) binds to B-adregenic receptors in cell membrane which are linked to G-proteins. Best guess for me would be hydrogen bonding as I seem to recollect that cAMP is involved in mediating this somehow. Sorry if it's not enough.

Answer 4

Is this any help?

http://en.wikipedia.org/wiki/Adrenaline

The "Pharmacology" section of the wiki might help, if not there are ample linked references which hopefully will.