Receptor concave

Binding of these ligands does not occur in a concave groove located on the surface of the receptor protein as otherwise often imagined. As described in Section 2.2.1, the x-ray structure of rhodopsin showed that retinal is bound deep in the seven-helical structure with major interaction points in TM-III and TM-VI, as well as the covalent attachment point in TM-VII. In fact, rhodopsin interacts with basically all transmembrane segments. Importantly, side-chains from the transmembrane helices cover the retinal molecule on all sides, and its binding site is found deep in the middle of... 

Computing properties, defined, 76 729-730 CoMSIA, pharmacophore generation and validation, 6 12 Concavalin A (Con A), 9 66-67 Concave receptor, 76 774 Concentrate, defined, 76 127 Concentration... 

Figure 7 shows how the solvent accessible surface of the enzyme CAC (hydrophobic space - red polar space - blue) is slightly concave about the substituent X of the sulfonamide (green). Similar rules exist for the coefficients which describe other aspects of hydrophobicity, as well as polar space, which help define the basic shape, t.e., cleft or hole, of the surface receptor model. 

Inside the cell, numerous chemical processes take place at the same time. The cell solves the problem of generating a large number of different molecules at the same time with a high selectivity by the use of enzymes. The selectivity of these proteins is largely determined by their geometry. Also the selectivity of another class of proteins, the receptors, is influenced by geometrical features. Receptors and enzymes have in common that they are equipped with concave structures such as clefts or cavities [1] in which substrate molecules are bound or chemically modified. 

Multivalent receptor with concave docking sites... 

Because earlier reviews deal explicitly with these template effects [4, 7, 12], the following discussion is restricted to a recently discovered anion template effect (Scheme 6.5.3). fn non-competitive solvents, the tetralactam macrocyde strongly binds anions such as chloride, bromide, or phenolate. Phenolate stoppers bound to the macrocycle can act as wheeled nudeophiles and react through the wheel with a semi-axle generated in situ to yield ether rotaxanes in yields of 57% to 95% [13]. Consequently, the macrocyde not only represents an anion receptor, but as a concave template simultaneously provides the correct orientation of the guest for threading the axle into the wheel. 

The larger the value of the exponent, the more curved (steeper, concave downwards) is the line. A very high exponent can be viewed as indicating an all-or-none effect (e.g. the development of an action potential in a nerve). Within a narrow concentration range, the observed effect goes from all to nothing or vice versa. An exponent less than unity (<1) sometimes indicates active metabolites and/or multiple receptor sites. 

Figure 35.3 PAMP-recognition unit of the Toll-like receptor. (A) The structure of the leucine-rich repeat (LRR) domain from human TLR-3. Notice that the LRR units come together to form a central parallel (3 sheet that curls to form a concave structure. (B) The structure of a single LRR showing the positions of the residues that are generally approximately conserved. Notice that the leucine residues come together to form a hydrophobic core with the single 3 strand along on one side. [Drawn from IZIW.pdb],...

---