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501.
Radial locations of amino acid residues in a globular protein: correlation with the sequence 总被引:8,自引:0,他引:8
The location measure of a residue in a globular protein is defined as the number of C alpha atoms surrounding the residue located within a sphere of the radius of 14 A. This quantity is a measure of the exposure of a residue to solvent, and is related closely to the distance from the center of mass of a protein. In this work, the experimental value for each residue of a protein is obtained from the X-ray crystallographic data, and the quantity is also calculated from the amino acid sequence data by applying an empirical parameter set to it. The correlation between the experimental and computed quantities is as high as 0.50 on the average over 92 proteins of known three-dimensional structure. Therefore, the location measure of every residue in a globular protein is predictable with good accuracy from the sequence. 相似文献
502.
A novel method that we have developed in the preceding paper to study the subunit exchange rates of F-actin (N. Suzuki and K. Mihashi, Biophys. Chem. 33 (1989) 177) was applied to regulated F-actin (a complex of F-actin, tropomyosin and troponin). We found that the dynamic polarity of regulated F-actin is modulated in a Ca2+-dependent manner, giving rise to strong suppression of the on/off rates of subunit exchange at the P-end. We interpreted this characteristic suppression as follows. Removal of Ca2+ from troponin C in regulated F-actin produces strong constraints on fluctuations in potential energy of an intermediate conformation of the terminal structure (P-end) which would be formed in the course of association and dissociation of the actin subunit. 相似文献
503.
Ong Hean Tatt 《Biologia Plantarum》1980,22(4):249-254
Sucrose gradient analyses were made on free ribosomes extracted from Azuki bean seedling leaves subjected to mannitol induced
water stress. Comparisons were made of the effect of duration of stress and the effect of urea on the free ribosomes. The
capacities of the ribosomal fractions to incorporate amino-acids were also studied. Water stress reduced total free ribosomes
and proportion of polysomes in the ribosomes as well as the capacity of the ribosomes to incorporate amino-acids into proteins.
Polysomes which were broken down by the water stress also appeared to be more susceptible to denaturation and synthesized
different proteins than polysomes which remained in the leaves after water stress. 相似文献
504.
The β-coil transition of poly(S-carboxymethyl-L -cysteine) (poly[Cys(CH2CO2H)]) and poly(S-carboxyethyl-L -cysteine) (poly[Cys((CH2)2CO2H)]) was followed by CD, potentiometric titration, and viscosity in the absence of added salt. These different properties give consistent results for poly[Cys((CH2)2CO2H)]. The CD spectra of poly[Cys(CH2CO2H)] change considerably with the degree of neutralization α even for a low-molecular-weight sample incapable of forming the β-structure. Because of the superposition of this additional effect, the dependence of CD on α is inconsistent with titration data for the case of poly[Cys(CH2CO2H)], particularly when the nπ transition is used to follow the β-coil transition. The change of CD inherent to the β-coil transition is characterized by an isodichroic point: 215 nm for poly[Cys((CH2)2CO2H)] and 218 nm for poly[Cys(CH2CO2H)]. A criterion supporting the stacking of the pleated sheet is suggested based on the isodichroic point. 相似文献
505.
506.
507.
Evidence for an endothelial cell-derived factor which stimulates the growth of human peripheral blood mononuclear cells 总被引:1,自引:0,他引:1
Evidence is provided which demonstrates that conditioned media of cultured endothelial cells derived from human umbilical veins contained a factor which stimulated peripheral blood mononuclear cell [3H]thymidine uptake. A dose-dependent response in peripheral blood mononuclear cell [3H]thymidine uptake was obtained when cells were incubated with increasing concentrations of supernatant of endothelial cell cultures. Studies on temporal kinetics demonstrated that stimulatory activity was evident when mononuclear cells had been incubated with endothelial cell supernatant for 120 hr or more. Preliminary characterization showed the growth immunoregulatory factor to have a molecular weight greater than 100,000 Da. 相似文献
508.
H S Yong C S Ooi G L Chiang W H Cheong S S Dhaliwal 《Comparative biochemistry and physiology. B, Comparative biochemistry》1985,82(2):275-278
Three temporal samples of a wild population of Mansonia uniformis were analysed for genetic variation at six gene-enzyme systems. Adenylate kinase, hexokinase (3 loci) and cathodal malate dehydrogenase were monomorphic. Phosphoglucomutase, glucose phosphate isomerase, isocitrate dehydrogenase and anodal malate dehydrogenase were polymorphic. Each of the polymorphic loci was represented by three alleles. The average heterozygosity or gene diversity was 0.0437. 相似文献
509.
A 12-month study was carried out on the molecular epidemiology of rotavirus in urban and suburban Malaysian children. Analysis of faecal samples from 973 hospitalized diarrhoeic children by polyacrylamide gel electrophoresis detected 268 rotaviruses (28%). All isolates were group A rotaviruses, which produced 22 electropherotypes: 16 (91.5%) with long RNA migration patterns and 6 (8.5%) with short patterns. One of the long-pattern electropherotypes was the predominant strain (71.1% of the total electropherotypes) isolated during this study. Although 3 other strains were detected sporadically over the study period, 16 others were present only during the first 7 months and 2 others were confined to the last 5 months. Long- and short-pattern electropherotypes were found to co-circulate extensively. There was a significant association of short-pattern electropherotypes with infection in older children. In addition, the prevalence of vomiting and mean duration of diarrhoea were significantly associated with different electropherotypes. 相似文献
510.