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71.
The method for obtaining antisera to meningococci of different serotypes are described and the scheme for the preparation of serotyping is presented, as well as the method for the preparation of the determinate fraction of serotype 2. Antisera to typing antigens 1, 2, 2-7, 2-10, 4, 5, 6, 8 (1) have been obtained, their specificity tested in parallel experiments with American and French typing sera. When typing meningococci, the use of antisera to purified protein antigen 2 is recommended.  相似文献   
72.
The oxidative half-reaction of phenol hydroxylase has been studied by stopped-flow spectrophotometry. Three flavin-oxygen intermediates can be detected when the substrate is thiophenol, or m-NH2, m-OH, m-CH3, m-Cl, or p-OH phenol. Intermediate I, the flavin C(4a)-hydroperoxide, has an absorbance maximum at 380-390 nm and an extinction coefficient approximately 10,000 M-1 cm-1. Intermediate III, the flavin C(4a)-hydroxide, has an absorbance maximum at 365-375 nm and an extinction coefficient approximately 10,000 M-1 cm-1. Intermediate II has absorbance maxima of 350-390 nm and extinction coefficients of 10,000-16,000 M-1 cm-1 depending on the substrate. A Hammett plot of the logarithm of the rates of the oxygen transfer step, the conversion of intermediate I to intermediate II, gives a straight line with a slope -0.5. Fluoride ion is a product of the enzymatic reaction when 2,3,5,6-tetrafluorophenol is the substrate. These results are consistent with an electrophilic substitution mechanism for oxygen transfer. The conversions of I to II and II to III are acid-catalyzed. A kinetic isotope effect of 8 was measured for the conversion of II to III using deuterated resorcinol as substrate. The conversion of III to oxidized enzyme is base-catalyzed, suggesting that the reaction depends on the removal of the flavin N(5) proton. Product release occurs at the same time as the formation of intermediate III, or rapidly thereafter. The results are interpreted according to the ring-opened model of Entsch et al. (Entsch, B., Ballou, D. P., and Massey, V. (1976) J. Biol. Chem. 251, 2550-2563).  相似文献   
73.
The amino acid composition, N- and C-terminal amino acid sequences, and the basic physicochemical and immunochemical properties of the recently discovered pregnancy-associated molecular variant of human transcortin (Strel'chyonok, O.A., Avvakumov, G.V. and Akhrem, A.A. (1984) Carbohydr. Res. 134, 133-140) have been found to be identical to those of transcortin from normal donor serum. This suggests the identity of polypeptide moieties of the two glycoproteins. The transcortin variant has a lower isoelectric point (3.5-4.1) than normal transcortin (3.6-4.2), and different electrophoretic mobility in low-porosity polyacrylamide gel (one band versus two for normal transcortin). These differences can be reasonably explained by different organization of the carbohydrate moieties of these glycoproteins due to diverse post-translational modification of a single polypeptide chain. The levels of transcortin variant in the maternal venous serum throughout normal gestation (447 donors in all) and on the fifth day after delivery, as well as in umbilical cord serum and extracts of term placenta, have been measured by a radioimmune assay. Analysis of the data obtained allowed us to conclude that the biosynthesis of pregnancy-associated transcortin variant occurs in some organ of the maternal organism rather than in the feto-placental system, and it is a characteristic of pregnancy as a unique physiological state of the female organism rather than a phenomenon caused by individual features of certain women. We assume that the transcortin variant takes part in the guided transport of corticosteroids and/or progestins into some tissues that develop in the course of gestation.  相似文献   
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A method is described which allows a clear demonstration of capillaries and muscle fibers in the heart and skeletal muscle of experimental animals. The fluorescent dyes fluorescein isothiocyanate (FITC) and lissamine rhodamine B 200 (RB 200) were conjugated with a protein of high (gamma-globulin) and low (myoglobin) molecular weight, respectively, and were intravitally injected into the vascular system of rats. FITC globulin distributes itself in the intravasal space and RB 200 myoglobin in the extracellular. In histological sections the capillary lumina and the borderlines of the muscular fibers can be clearly identified and quantitatively evaluated because of the selective fluorescence in the respective structures.  相似文献   
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