Carbon secondary structure

Schiffbase, 1147 Scurvy vitamin C and, 772 sec-Butyl group, 84 Second-order reaction, 363 Secondary alcohol, 600 Secondary amine, 917 Secondary carbon, 84 Secondary hydrogen. 85 Secondary structure (protein), 1038-1039... 

The effect of C ,C -disubstituted amino acids (aaAAs) on peptide secondary structure has been studied in recent years.2a d While longer side-chain C ,C -di-n-alkyl amino acids promote extended peptide conformation,23 alicyclic aaAAs, in which the Ca carbon forms a cyclic bridge with itself, such a 1-aminocyclopentane-l-carboxylic acid (Ac5c) and 1-aminocyclohexane-l-carboxylic acid (Ac6c), have helix-forming characteristics similar to those of 1 -aminoisobutyric acid (Aib).2ax... 

However, if side-chain carbon assignments are wanted, C(CC)(CO)NH experiments [33] that start directly with carbon magnetization and transfer it further to the amide proton for detection are available. If protonated substituents, for example methyl groups, have been introduced into the otherwise perdeuterated protein, the usual HC(C)(CO)NH-TOCSY pulse sequence can be used to obtain the proton chemical shifts. These protons can provide a small number of NOEs that, together with residual dipolar couplings and the secondary structure identification from chemical shifts, make the determination of the global fold of large proteins possible. 

Site of the. acidic surface oxides. The question whether the acidic surface oxides are bound to the periphery of the carbon layei-s or to the basal planes of the crystallites could be resolved by oxidation of a graphitized carbon black (46). The particles of carbon black are, at first approximation, spherical. The graphite-like crystallites show such preferential orientation that their c axis are aligned in a radial direction (64, 65). A schematic representation of this secondary structure is given in Fig. 1. On recrystallization between 2000 and 3000°, many small... 

Synthetics and mineral fibers have other parallels. A few synthesized fibers show a higher level or secondary ordering of the crystalline structure, such as that described for chrysotile. Composed entirely of carbon, graphite fibers are synthetic fibers with such a secondary structure (see the following section). Tubular fibers of other compositions, such as aluminum silicate polymers, have also been synthesized (Farmer et al., 1977). 

The best calculation method indicates that N-2 is slightly positive while N-3 and N-4 are electron rich. The methyl carbon is nearly neutral. Resonance diagrams of the calculated primary configuration and the secondary structure give information about bond orders and orbital overlap. 

Control of the selectivity of the addition often is best achieved by choosing the proper reactants. The major influence is steric. The organic portion of the organopalladium intermediate normally adds to the less-hindered, double-bond carbon of the olefin. The secondary electronic effect is to cause the organic group to add to the more electron-deficient double-bond carbon. The structure of the vinylic halide also may influence the selectivity of the addition. Both vinyl bromide and 2-bromopropene (and other internal vinylic halides) add... 

---