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排序方式: 共有2799条查询结果,搜索用时 17 毫秒
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PR Burchat GJ Feldman T Barklow AM Boyarski DL Burke JM Dorfan L Gladney G Hanson K Hayes RJ Hollebeek WR Innes JA Jaros D Karlen AJ Lankford RR Larsen BW LeClaire NS Lockyer V Lüth C Matteuzzi RA Ong ML Perl B Richter K Riles MC Ross JM Yelton C Zaiser GS Abrams D Amidei AR Baden J Boyer F Butler G Gidal MS Gold G Goldhaber L Golding J Haggerty D Herrup I Juricic JA Kadyk ME Nelson PC Rowson H Schellman WB Schmidke PD Sheldon GH Trilling de la Vaissiere C DR Wood ME Levi T Schaad 《Canadian Metallurgical Quarterly》1987,35(1):27-41
144.
CA Millar LC Campbell DL Cope DR Melvin KA Powell GW Gould 《Canadian Metallurgical Quarterly》1997,25(3):974-977
The available data suggest that GLUT4 does populate the recycling endosomal system to some extent, but that a large proportion of the intracellular GLUT4 resides in a compartment that is devoid of transferrin receptors and may have properties more akin to specialized secretory vesicles. The study of the nature and biogenesis of this compartment will provide important insight into the mechanism by which insulin stimulates glucose transport. Further study of the role of the synaptobrevins in these distinct subcellular compartments will probably shed further light on the mechanism by which insulin stimulates GLUT4 translocation. 相似文献
145.
A model system for cytochrome P-450 comprised of hemin, thiosalicylic acid, and solvent (acetone and water), oxidized cyclohemne and n-hexane at pH 2.7. Oxidation of cyclohexane yielded more cyclohexanol than cyclohexanone under mild reaction conditions, whereas the oxidation of n-hexane generated more 3- and 2-hexanones than 3- and 2-hemnols. Oxygen was a limiting factor in the reaction, and increased oxygen pressures increased the ratio of cyclohexanone to cyclohexanol formed. Lag time for product formation decreased in a linear fashion with an increase in temperature. In addition, cyclohexanone decreased relative to cyclohexanol as the temperature was increased. Antioxidants increased the lag time for product formation, but had little effect on the final quantity or ratios of the oxidative products generated. 1,3 Diphenylisobenzafiran had no effect on the lag time, whereas Tiron and catechol increased the lag time. In contrast to aliphatic thiols, aromatic thiols were capable of driving the oxidative reaction. The model hemin system was approximately 6% as active as natural cytochrome P-450. Hemin immobilized on glass beads effectively catalyzed the oxidation of cyclohexane. 相似文献
146.
Feil IK; Platas AA; van den Akker F; Reddy R; Merritt EA; Storm DR; Hol WG 《Protein engineering, design & selection : PEDS》1998,11(11):1103-1109
Members of the cholera toxin family, including Escherichia coli heat-
labile enterotoxins LT-I and LT-II, catalyze the covalent modification of
intracellular proteins by transfer of ADP-ribose from NAD to a specific
arginine of the target protein. The ADP-ribosylating activity of these
toxins is located in the A-subunit, for which LT-I and LT-II share a 63%
sequence identity. The flexible loop in LT-I, ranging from residue 47 to
56, closes over the active site cleft. Previous studies have shown that
point mutations in this loop have dramatic effects on the activity of LT-I.
Yet, in LT-II the sequence of the equivalent loop differs at four positions
from LT-I. Therefore five mutants of the active site loop were created by a
stepwise replacement of the loop sequence in LT-I with virtually all the
corresponding residues in LT- II. Since we discovered that LT-II had no
activity versus the artificial substrate
diethylamino-benzylidine-aminoguanidine (DEABAG) while LT-I does, our
active site mutants most likely probe the NAD binding, not the arginine
binding region of the active site. The five hybrid toxins obtained (Q49A,
F52N, V53T, Q49V/F52N and Q49V/F52N/V53T) show (i) great differences in
holotoxin assembly efficiency; (ii) decreased cytotoxicity in Chinese
hamster ovary cells; and (iii) increased in vitro enzymatic activity
compared with wild type LT-I. Specifically, the three mutants containing
the F52N substitution display a greater Vmax for NAD than wild type LT-I.
The enzymatic activity of the V53T mutant is significantly higher than that
of wild type LT-I. Apparently this subtle variation at position 53 is
beneficial, in contrast to several other substitutions at position 53 which
previously had been shown to be deleterious for activity. The most striking
result of this study is that the active site loop of LT- I, despite great
sensitivity for point mutations, can essentially be replaced by the active
site loop of LT-II, yielding an active 'hybrid enzyme' as well as 'hybrid
toxin'.
相似文献
147.
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M Maes DR Van Bockstaele A Gastel C Song C Schotte H Neels I DeMeester S Scharpe A Janca 《Canadian Metallurgical Quarterly》1999,39(1):1-9
This study aimed to investigate which abilities are measured by the Austin Maze. One hundred and eight university students were administered a battery of eight neuropsychological tests including, the Austin Maze, the Tower of London, the Wisconsin Card Sort Test, Block Design, the Visual Spatial Learning Test, Digit Span Backwards, the Brown-Peterson Task and the Wide Range Achievement Test of Reading. Results indicated that visuospatial ability and memory both significantly contributed to performance on the Austin Maze, but differed in the degree to which they explained the performance depending on which measure of maze performance was employed. It appears that visuospatial ability is measured in early trials of the Austin Maze when individuals are orienting themselves to the path. In later trials individuals must call upon visuospatial memory to consolidate the details of the path. Executive function and working memory were not found to be significantly implicated in performance on the Austin Maze. 相似文献
150.