Arginine remarkably prolongs the lifetime of the M-intermediate in the bacteriorhodopsin photocycle at room temperature

AbstractThe lifetime of the M-intermediate in the bacteriorhodopsin photocycle was remarkably prolonged on drying a suspension of purple membrane, in arginine solution at alkaline pH. The M-intermediate could be completely accumulated under illumination (530 nm) at room temperature. The crystalline structure of purple membranes was retained after this treatment. The lifetime of the M-intermediate was found to be longer than 100 s and depended on the pH of the purple membrane suspension before drying. It was suggested that an interaction between the guanidium group of arginine and an amino acid residue played an important role in the prolongation

Trimeric mutant bacteriorhodopsin, D85N, shows a monophasic CD spectrum

AbstractThe structure of mutant bacteriorhodopsin (bR), D85N, was examined by CD and X-ray diffraction at pH 7. The absorption maximum of D85N at pH 7 is located at 605 nm, which is similar to the acid-blue form of wild-type bR. D85N shows a monophasic CD band, the maximum of which is at 575 nm, although the crystalline arrangement and the trimeric structure is maintained. The acid-blue form of wild-type bR shows a biphasic CD despite the similarity in absorption spectra

Properties of the Disorder Induced in the Purple Membrane Structure by Iodination

Iodination induces disorder in the crystalline structure of purple membrane. The properties Of the disorder were examined by X-ray diffraction experiments on the iodinated purple membrane. The analysis of the intensity and the integral width of the Bragg reflections revealed that the disorder was well characterized by the second kind of disorder. The g value, which represents the extent of the second kind of disorder, is obtained for iodinated purple membrane with various extent of iodination. The g value and the wavelength at absorption maximum of iodinated PM are well correlated, indicating that the local change around retinal is reflected in the disorder in the crystalline structure of purple membrane

SORL1 Is Genetically Associated with Late-Onset Alzheimer’s Disease in Japanese, Koreans and Caucasians

To discover susceptibility genes of late-onset Alzheimer’s disease (LOAD), we conducted a 3-stage genome-wide association study (GWAS) using three populations: Japanese from the Japanese Genetic Consortium for Alzheimer Disease (JGSCAD), Koreans, and Caucasians from the Alzheimer Disease Genetic Consortium (ADGC). In Stage 1, we evaluated data for 5,877,918 genotyped and imputed SNPs in Japanese cases (n = 1,008) and controls (n = 1,016). Genome-wide significance was observed with 12 SNPs in the APOE region. Seven SNPs from other distinct regions with p-values ,261025 were genotyped in a second Japanese sample (885 cases, 985 controls), and evidence of association was confirmed for one SORL1 SNP (rs3781834, P=7.3361027 in the combined sample). Subsequent analysis combining results for several SORL1 SNPs in the Japanese, Korean (339 cases, 1,129 controls) and Caucasians (11,840 AD cases, 10,931 controls) revealed genome wide significance with rs11218343 (P=1.7761029) and rs3781834 (P=1.0461028). SNPs in previously established AD loci in Caucasians showed strong evidence of association in Japanese including rs3851179 near PICALM (P=1.7161025) and rs744373 near BIN1 (P = 1.3961024). The associated allele for each of these SNPs was the same as in Caucasians. These data demonstrate for the first time genome-wide significance of LOAD with SORL1 and confirm the role of other known loci for LOAD in Japanese. Our study highlights the importance of examining associations in multiple ethnic populations