Conformation designation

The binding change mechanism for the trimeric Fi component resembles the action of a Wankle (or rotary) engine used in some automobiles. Fi s cylinders are made up of three identical polypeptide chains, and each protomeric unit is in a different conformation (designated L for Loose , T for Tight , and O for Open ). ADP and Pi bind to the L-site. Then, an energy-driven step occurs that successively converts L-ADP-Pi to T-ATP and T ATP to O + ATP ... 

The 2,3-dihydro-l //-l, 4-bcnzodiazepin-2-ones exist as an equilibrium mixture of two conformers, designated by the helical descriptors M and P, that reflect chirality associated with the 7 -N(l)-C(7)-C(8) dihedral angle (Scheme 1). The interconversion barrier between the M- and P- atropoisomers is dependent upon the size of the N-l substituent with AG = 12.3, 18.0, 21.1, and >24 kcal mob1 for H, Me, /-propyl, and /-butyl, respectively, a function of increasing... 

Most biochemical databases request the user to enter keywords to search/retrieve information concerning biomolecules (unless the identifiers of the compounds are known). The keyword is normally the IUBMB (International Union of Biochemistry and Molecular Biology) name or common name of the compound. In particular, the linkage and conformational designations of oligomeric compounds needs to be specified. The IUBMB nomenclature for biochemical compounds can be accessed from the IUBMB site at http //www.chem.qmw.ac.uk/iubmb/. Some useful databases for biochemical compounds are listed in Table 5.3. 

Chelate rings, such as that formed when ethane-1,2-diamine binds to a metal, commonly adopt one of two enantiomerically related conformations, designated S and X, as described in Section 17.3. 

Each protomer can exist in either of two conformations, designated R and T these originally referred to relaxed and tense, with the latter not being catalytically active. 

For a review, in English, of computer-aided conformational design in macrolide synthesis (including carbonolides) see O. Yonemitsu, Yuki Gosei Kagaku Kyokaishi, 1994, 52, 946. 

The pyranose ring conformations that are important in polysaccharides are the two chair conformations, designated and Q (Fig. 10) to indicate the disposition of atoms above and below the plane of the ring (in older notation the same conformations were denoted by Cl and 1C, respectively). Boat conformations probably have some existence in low proportions in disordered (random coil) polysaccharide chains. 

Protomers can exist in two conformations (designated T[ense] low affinity for substrate, R[elaxed] high affinity for substrate) that are in equilibriimi whether or not ligand is boimd ... 

Unfortunately, the rule that above the definition plane of a particular conformer is the direction from which the carbon atom numbers increase round the ring has the effect of reversing conformational designations between enantiomers - the mirror image of a-D-glucopyranose in the Ci conformation is oc-L-glucopyranose in the conformation. 

In this section only globular proteins will be considered. Their tightly folded native conformation (designated N) may change into a more or less unfolded conformation (U). This change may be called denaturation, but the conformation change may be reversible, and several authors reserve the word denaturation for irreversible unfolding, or for the loss of a specific activity. 

Some proteins exhibit at some pH values, for instance, about three units below the isoelectric pH, an intermediate conformation designated molten globule state . Such a state appears to be characterized by... 

Figure 5.1 Esterification of p-tert-butylcalixldfiirene (4 ) with 3,5-dinitrobenzoyl chloride. For viewing convenience the conformational designations start with the left-hand residue and proceed in clockwise fashion around the ring, with the reference residue specified with an underlined u or rf see Section 4.1)...

An additional and very important dimension is provided by the fact that many of the species shown in Figure 8.6 can exist in two different conformations designated syn and anti. This applies to butadiene whether as the di-7r forms I and III or the TTsa forms lA and lllB (IIIA can only adopt the syn form), and to the half-hydrogenated butenyls formed therefrom. Now in the gas phase the anti conformation of butadiene is preferred to the syn by a factor of about 20 at room temperature,so direct chemisorption into any of these structures (not going via II) automatically favours the former, and this geometry is maintained after the first hydrogen atom is added. The 713-butenyls cannot interconvert, except via IV, V and VII a temporary detachment of the r-bond from the surface, followed by... 

Conformation designates the spatial structure assumed by macromolecules of the same configuration by means of rotation about their bmid axes. The schematic drawing shows this in frontal and lateral views of two macromolecule chains C C C... 

Figure 4 shows several conformations designated quasiequatorial (essentially equivalent to intra), i.e., the ring N-C bond inside the inter-planar fold, coplanar, and quasiaxial (essentially equivalent to extra). Several workers claimed a preference for an extra or quasiaxial CPZ HCl conformation. Fronza and colleagues also claimed that the intra ring N-substituent bond is favored for phenothiazine but not for phenothiazine derivatives. In solids the orientation of the N-C bond was found to be closer to intra than extra, and probably closer to a flatter set of ring N bonds. 

The objective is to manufacture and sell safe products and not waste time arguing with customers who challenge a product s conformity. Designing and certifying products to meet the EU regulations may be more profitable than the oftentimes endless discussions and meetings within a company about the possible benefits. In the end, it s the customer s safety concerns that wilt determine whether the product is a success. Also remember that when a product becomes suspect, enforcement authorities will most likely refer the product to a notified body for testing and assessment. 

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