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81.
The Fv fragment of a monoclonal antibody, 7E2 (IgG1, κ, murine), which is directed against the integral membrane protein cytochrome c oxidase (EC 1.9.3.1) from Paracoccus denitrificans, was cloned and produced in Escherichia coli. Crystals suitable for highresolution X-ray analysis were obtained by microdialysis under low salt conditions. The crystals belong to the orthorhombic space group P212121 with unit cell dimensions of a = 51.51 Å, b = 56.15 Å, c = 99.86 Å (1 Å = 0.1 nm) and contain one F v fragment per asymmetric unit. Using synchrotron radiation diffraction data were collected up to 1.28 Å resolution. This high resolution is very unusual for a heterodimeric protein. The crystals should open the way for refining not only the atomic positions, but also for obtaining information about internal dynamics. © 1995 Wiley-Liss, Inc. 相似文献
82.
A new monoclonal antibody (3D3) generated with human respiratory mucins and directed against Lewis determinants 总被引:1,自引:1,他引:0
Nathalie Emery; Palfa Shirley B.; Place Graham; Oriol Rafael; Hall Roderick L.; Roussel Philippe; Lhermitte Michel 《Glycobiology》1995,5(6):563-570
We have prepared a monoclonal antibody (MAb), 3D3, raised againstpurified human respiratory mucins. This antibody recognizedmucins and proteolytically derived glycopeptides. The epitoperecognized by the antibody was destroyed by -L-fucosidase, indicatingthat it was present on the carbohydrate moieties. Structuralspecificity was determined by adsorption on a variety of synthetic,insolubilized oligosaccharides. Several lines of evidence indicatethat the 3D3 MAb reacted strongly with the Lewis (Leb) antigen,but also recognized Lea and Ley determinants. This antibodymight be useful to study mucin secretion. human bronchial mucins Lewis b 相似文献
83.
We demonstrate how the progressive passage through an interface simulated by a linear increase in dielectric constant may mediate a reversible transconformation of Na+/X337A (lasalocid A) from a cyclic to an extended structure, During the passage through the interface, the complex adopts progressively a more extended conformation favorable to the Na+ complexation or decomplexation at the interface. 相似文献
84.
Target size analysis by radiation inactivation is widely used for molecular weight determination of membrane enzymes and receptors in situ without the need for prior solubilization or purification. However, since most molecular weight data available in the literature on membrane proteins involve the use of detergents for solubilization, the target sizes of membrane proteins in situ and after solubilization by detergent treatment have been compared. Using data from the literature and personal results, three different types of behavior of membrane proteins in presence of detergents were found: (i) uncoupling of subunits (electric eel acetylcholinesterase, placental steroid sulfatase, and human nonspecific β-glucosidase); (ii) coupling of protein molecules (mouse liver neuraminidase, and rat liver insulin receptor regulatory component); and (iii) no major change in quaternary structure (rat liver insulin receptor, kidney γ-glutamyltransferase, asialoglycoprotein receptor, insulin degrading enzyme, and human leucocyte neuraminidase). For all these proteins, there is a statistically significant increase in target size of about 24% over the value obtained in situ without detergent. A relatively large body of literature data involving a variety of membrane proteins, membrane types, and irradiation conditions (electron accelerators or 60Co sources, and proteins irradiated in lyophilized form or frozen solution) was examined, and it was concluded that target sizes of membrane proteins, irradiated in the presence of Triton X-100, should be diminished by a factor of about 24% to obtain the molecular weight value. 相似文献
85.
Overbeeke Nico Haring Michel A. John H. Nijkamp J. Kool Ad. J. 《Plant molecular biology》1984,3(4):235-241
Summary Sequences from Petunia hybrida chloroplast DNA which have the property to promote autonomous replication in Saccharomyces cerevisiae were cloned in vector YIp5. Seven cloned chloroplast DNA fragments are localized at one of two different sites on the chloroplast genome. One site, arsA was mapped on a 1.8 Kb fragment at position 27.0–28.8 Kb on the P. hybrida chloroplast genome. The plasmids containing this arsA are stable both in yeast and E. coli. The other site, arsB, was shown to be very unstable and is located either in the small single copy region close to the inverted repeat or just in the inverted repeat. The functioning of these sequences as a possible origin of replication in vivo is discussed. 相似文献
86.
Summary To estimate the background fetal loss rates among women who might be candidates for chorionic villi sampling (CVS) for prenatal diagnosis, we examined the frequency of spontaneous abortion and of non-viable fetuses in two groups of women thought to be pregnant at 8–12 weeks' gestation. Among 1519 women over 35 years given an appointment for amniocentesis 1978–1981, 9.8% had a spontaneous abortion prior to 16 weeks' gestation. For those under observation before week 12, the loss rate by 16 weeks was 15.3%. Among all 190 candidates for elective termination of pregnancy between 6 and 12 weeks' gestation, 12.6% were found to have a non-viable fetus at the scheduled date of abortion. The frequency of non-viability was 14% among those seen before week 12. The data suggest that the background loss rate between the time of CVS and the time of amniocentesis is approximately 1–2% and is unlikely to be higher than 9%. Until randomized clinical trials of the procedure are completed we will not know how much, if at all, the loss rate associated with CVS is increased above this background. Nevertheless, knowledge of these background risk estimates may be useful in counseling women considering participating in trials of CVS. 相似文献
87.
Characterization of a New Type of Human Papillomavirus That Causes Skin Warts 总被引:12,自引:6,他引:6 下载免费PDF全文
A human papillomavirus (HPV) was isolated from the lesions of a patient (ML) bearing numerous hand common warts. This virus was compared with the well-characterized HPV found in typical plantar warts (plantar HPV). ML and plantar HPV DNAs have similar molecular weights (5.26 x 10(6) and 5.23 x 10(6), respectively) but were shown to be different by restriction enzyme analysis. When the cleavage products of both DNAs by endonuclease EcoRI, BamI, HpaI, or Hind were analyzed by electron microscopy, one, two, one, and four fragments were detected for ML HPV DNA instead of the two, one, two, and six fragments, respectively, detected for plantar HPV DNA. In contrast to plantar HPV DNA, a high proportion of ML HPV DNA molecules were resistant to these restriction enzymes. Most, if not all, of the molecules were either resistant to BamI and sensitive to EcoRI or sensitive to BamI and resistant to EcoRI. After denaturation and renaturation of the cleavage products of ML HPV DNA by a mixture of the two enzymes, the circular "heteroduplexes" formed showed one to three heterology loops corresponding to about 4 to 8% of the genome length. No sequence homology was detected between ML and plantar HPV DNAs by cRNA-DNA filter hybridization, by measuring the reassociation kinetics of an iodinated plantar HPV DNA in the presence of a 25-fold excess of ML HPV DNA, or by the heteroduplex technique. The two viruses had distinct electrophoretic polypeptide patterns and showed no antigenic cross-reaction by immunodiffusion or immunofluorescence techniques. Preliminary cRNA-DNA hybridization experiments, using viral DNAs from single or pooled plantar or hand warts, suggest that hand common warts are associated with viruses similar or related to ML HPV. The existence of at least two distinct types of HPVs that cause skin warts was demonstrated; they were provisionally called HPV type 1 and HPV type 2, with plantar HPV and ML HPV as prototypical viruses, respectively. 相似文献
88.
J Hofmann U Till B Hofmann E Michel M Quiess 《Acta biologica et medica Germanica》1979,38(8):1149-1157
Two processes are involved in the accumulation of acridine orange in human blood platelets. One follows a diffusion like kinetics and is independent of the ATP level whereas the second one can be completely abolished by ATP depletion. The acridine orange incorporation rate seems to be a suitable parameter for testing platelet integrity. It reflects very sensitively the influence of the preparation method as well as of anticoagulating substances used on the stability of platelet suspensions. The rates of acridine orange incorporation and of aggregation were measured in platelet-rich plasma and in saline suspended platelets after gel filtration, respectively, over a period of 120 min storage. Both rates are influenced to a different degree by anticoagulating agents such as citrate, heparin and EDTA. When contact with anticoagulating agents during platelet preparation is avoided, platelets show a constant acridine orange incorporation and aggregation during storage and the smallest morphological alteration. 相似文献
89.
Agarose gel electrophoresis offers a versatile means to fractionate nucleic acids varying in size over considerably different molecular weight ranges. Surface cohesion properties of agarose gels and sample loading problems have hampered the use of such gels in largediameter, preparative-scale tube gel electrophoresis. We report here a procedure that makes routine and reproducible the construction, sample loading, and running of preparative agarose electrophoretic gels. Data are presented on the fractionation of yeast nucleic acids. 相似文献
90.
In 234 copulations, male and female behavioural patterns were collected, especially the vocal pattern for the female. Moreover
quantitative structural analysis was performed on 38 of these female copulatory vocalizations. A multifactorial analysis,
ANAFAC, was performed to seek relations between (1) utterance of female copulatory call and male and female copulatory behaviour
and (2) these patterns and the great variability of female calls. Utterance of female copulatory vocalizations is essentially
due to the female’s own copulatory behaviour in periods of intense sexual activity. Long female calls are related to male
ejaculation, and those “rich” in harmonics are related to visual and tactile communicatory signals exchanged by the male and
the female during a mount. This analysis strongly confirms the tied bond between quality of a call and internal state of the
emitter. Long calls, rich in harmonics, may serve as signals maintaining or strengthening the possibly temporary preferential
relation between male and sexually receptive female. 相似文献