Protein side-chain conformations were examined by searching for all combinations of the side-chain rotamers, with energies near the global minimum, that were found in advance by the dead-end elimination algorithm. Using this method, the side-chain configurational entropies and their correlations were analyzed for the hydrophobic sides of the secondary structures of proteins. The conformations of several bulky side-chains in α-helices were found to be cooperatively fixed by the restricted side-chain conformations of the neighboring β-branched amino acids. In β-sheet, the side-chain conformations are not restricted by the backbone structures of the individual β-strands, but those in the inner stands are restricted, due to the correlation between the side-chains on the neighboring strands.
Protein side-chain configurational entropies and their correlations were analyzed for α-helices in several proteins. The conformations of several bulky side-chains in helices were found to be cooperatively fixed by the restricted side-chain conformations of the neighboring β-branched amino acids. Such helices correspond well to the experimentally observed nuclei in the folding procedures, so that the folding rates should be significantly accerelated. This phenomenon may be a reasonable answer to the Levinthal paradox.
Effects of constant magnetic field (CMF, 0.65T) on muscle tension were studied in the bullfrog sartorius muscle. Muscles were stimulated every 30mins during exposure to a CMF for up to ten hrs. Tension developed at each time point decreased with time. However, the rate of decrease was smaller for test than for control muscles, and tension was larger in test than in control muscles.
Borna disease virus (BDV), a nonsegmented, negative-sense, single-stranded RNA virus with an envelope, was initially isolated from horses with poliomyeloencephalitis. BDV is also believed to be linked with psychiatric disorders in humans based on higher prevalences of serum antibodies against BDV and viral RNA footprints in peripheral blood mononuclear cells of psychiatric patients, compared with those of controls. Here, we show that BDV RNA was identified in total RNA extracted directly from clinical samples of brain tumors. We found that two and three samples were positive using primers for the p24 and p40 regions, respectively, among grade 4 malignant tumors (glioblastomas) from 16 patients. There were no positive samples among lower grades of tumors (pilocytic or anaplastic astrocytomas) from 21 patients at either region. Of particular note is the detection of either a p40 or a p24 RNA in each of the tumor samples. Thus, we detected BDV RNA for the first time in the brains of immunosuppressed patients.