Computer modelling of the interaction between human choriogonadotropin and its receptor

Primary structural homology between the hormone binding site of the LH/CG receptor and the enzyme binding site of chymotrypsin inhibitor has been identified. This has led to the application of a knowledge-based approach of molecular modelling to describe the interaction of choriogonadotropin (CG) with the LH/CG receptor. A tertiary structural model for the mode of recognition between the hormone and the receptor has been proposed. As in other such processes at the molecular level, the recognition between CG and its receptor is mediated through non-covalent interactions. The specificity of recognition is achieved by complementarity in van der Waals surfaces, hydrogen bonding and non-polar associations. The model shows nine hydrogen bonds between the hormone and the receptor involving polar side chains as well as backbone amine and carbonyl groups. A hydrophobic cluster involving side chain groups at the interface is also important in stabilization of the intermolecular interactions.