[Left-handed helix conformation of poly-L-proline II type in globular proteins. Statistics of incidence and a role of sequence]. / Levospiral'naia konformatsiia tipa poli-L-prolin II v globuliarnykh belkakh. Statistika vstrechaemosti i rol' posledovatel'nosti.

Regions of left-handed polyproline II type conformation in globular proteins were studied throughout the PDB bank. The length and sequence of corresponding fragments were analyzed. It was found that a lot of tetrapeptides (from combinatorial possible ones) show the tendency to be included in the left-handed helices. Much more tetrapeptides do not occur in this structure type.

[Double and bifurcated hydrogen bonds in alpha-helices of globular proteins]. / Dvoinye i vilochkovye vodorodnye sviazi v al'fa-spiraliakh globuliarnykh belkov.

The statistical analysis of hydrogen bonds distribution in space structures of globular proteins has been done. The parameters of H-bonds in the different secondary structures of globular proteins were collected. In alpha-helices besides the canonical 1-5 H-bonds (the mean length 3 A), 1-4 H-bonds were observed (the mean length 3.2 A). The histograms of length and angular distributions of the bonds are presented. It was found on the basis of quantum chemistry calculations that most H-bonds in alpha-helices are double or bifurcated.