Escherichia coli neuraminidase

The intracellular form of neuraminidase has been detected in E. coli and Proteus vulgaris. Neuraminidase has been isolated from E. coli HB 101 cells and purified 118-fold. Some physico-chemical properties of this enzyme have been studied.     

Conformations of blood group H-active oligosaccharides of ovarian cyst mucins

Spectroscopic data and conformational energy calculations are reported for eight oligosaccharides from ovarian cyst mucins and from human milk, the nonreducing terminals of which have fucose (α1 → 2)galactose linked either (β1 → 3) (type I) or (β1 → 4)(type II) to N-acetylglucosamine or in (β1 → 3) linkage to galactosaminitol. The fully assigned proton nmr spectra are reported along with nuclear Overhauser enhancement (NOE) data. Amide proton coupling constants and vacuum-uv CD spectra provide information on the amide plane orientation and amide environment. Our results imply that the fucosidic dihedral angles are similar for all three cases and that the substantial differences in the chemical shifts of the fucosyl protons of type I, type II, and 3-ol chains result from different perturbations by the amide group of the residue to which the β-galactose is linked. Stereopair diagrams of conformational models for both type I and II H chains are presented that are consistent with NOE, coupling constants, conformational energy calculations, and the CD data. While the temperature dependence of the observed NOE of penta- and hexasaccharides indicates that their rotational correlation times are strongly temperature dependent, we conclude that the conformations are essentially independent of temperature.     

Localization of carbonic anhydrase in the rat lung

Summary The localization of carbonic anhydrase in the rat lung has been demonstrated, at light and electron microscopic levels, by the cobalt bicarbonate histochemical method of Hansson. Focal deposits of the cobalt sulfide reaction product were found not only in the capillary endothelium of the alveolar walls, but also in the small and large alveolar cells. The histochemical reaction was abolished by two potent inhibitors, acetazolamide (10^–5 to 10^–6 M) and KCNO (5×10^–3 to 10×10^–3 M). Physiological assay with Maren's method indicated that values for carbonic anhydrase activity in rat lung are 4.4±0.8 UA/mg of protein, 25.0±5.5 UA/mg of nitrogen, and 369±86 UA/g of wet weight. In addition, it was calculated that after fixation in glutaraldehyde-formaldehyde-picric acid about 9% activity is retained.     

Immunochemical properties of mannan-protein complex isolated from viable cells of Saccharomyces cerevisiae 4484-24D-1 mutant strain by the action of zymolyase

Viable cells of Saccharomyces cerevisiae 4484-24D-1 mutant strain were treated with an Arthrobacter sp. beta-1,3-glucanase, Zymolyase-60,000, in the presence of a serine protease inhibitor, phenylmethylsulfonyl fluoride. Fractionation of the solubilized materials with Cetavlon (cetyltrimethylammonium bromide) yielded a purified mannan-protein complex, which had a molecular weight of ca. 150,000, approximately three times higher than that of the mannan isolated from the same cells by the hot-water extraction method at 135 C. The amino acid composition of the mannan-protein complex was found to be very similar to that of the mannan-protein complexes of S. cerevisiae X2180-1A wild and S. cerevisiae X2180-1A-5 mutant strains, indicating the presence of large amounts of serine and threonine. It was unexpected that the antibody-precipitating activity of this complex against the homologous anti-whole cell serum was about twice as great as that of the mannan isolated by hot-water extraction. Treatment of this complex with 100 mM NaOH, hot water at 135 C, and pronase, respectively, gave degradation products having the same molecular weight and antibody-precipitating activity as those of the hot-water extracted mannan, allowing the assumption that the protein moiety participated in a large part of this activity.     

Changes in mouse submaxillary glands after injection of isoproterenol in intact and depancreatized animals

The changes in the relative weight, cell area and ultrastructure of the submaxillary glands (SMG) of CBA/C57BL mice and those in the content of immunoreactive insulin-like protein (IRILP) occurring in the organ were studied. The changes were examined on day 6 after isoproterenol (ISP) injection (23 mg/100 g bw) to healthy animals (group I), on day 13 after pancreatectomy and on day 6 after injection of the indicated dose of ISP (group II), and on day 13 after pancreatectomy without ISP injection (group III). Intact animals served as control. In all the three experimental groups, the ratio between the SMG weight and the total weight of animals showed a tendency towards increase. The highest increase was recorded in group II, where the weight of the SMG was 46.1% higher than the control value. In groups II and III, the area of acinar cells increased by 49.1 and 12.5%, respectively. The area of salivary tube granular ducts decreased by 12.6% in group II and slightly increased (by 4.7% much greater than in group III. Electron microscopy demonstrated that secretory activity of the granular duct cells was enhanced in all the three groups and that secretory extrusion occurred via the apocrine (in group II animals via the holocrine as well) cells. The radioimmunoassay data suggest that IRILP content in the SMG of controls and animals entering groups I-III was 685 +/- 50, 1125 +/- 125, 914 +/- 120 and 302 +/- 66 mu units/g weight, respectively. It is concluded that the synthesis and accumulation of IRILP in the SMG after ISP injection are activated and that the formation and extrusion of IRILP after ISP injection to diabetic animals are overtly activated. Presumably ISP injection to diabetic mice facilitates the stimulation of the compensatory function of the SMG as an IRILP-producing organ.     

Immunocytochemical localization of somatostatin in the brain of the lizard, Ctenosauria pectinata

The brain of the lizard, Ctenosauria pectinata, was studied light microscopically using an immunocytochemical staining method that is specific for neurohypophysial hormones and somatostatin. It was shown that the telencephalon and particularly the diencephalon contain somatostatin-producing perikarya, while somatostatinergic fibers occur in the entire brain. Similar to the situation in other vertebrates, somatostatin neurons in Ctenosauria pectinata form a population distinct from the neurohypophysial hormone-producing neurons. The small-sized somatostatin neurons were found in the cortex and the diencephalon: (1) ventral from, and partially overlapping with, the classical neurosecretory paraventricular nucleus; and (2) in the region of the infundibular (tuberal) nucleus. Somatostatin fibers were found among the classical neurosecretory fibers of the supraoptico-paraventricular system (tract, median eminence, neural lobe), near to and within the epiphysis, in the septum, in the vicinity of the tectum opticum and the cerebellum, and in the tegmentum.     

Regulation of pathways of glucose metabolism in kidney. The effect of experimental diabetes on the activity of the pentose phosphate pathway and the glucuronate-xylulose pathway.

Measurements have been made of the activities of enzymes of the pentose phosphate pathway, the glucuronate-xylulose pathway, hexokinase and phosphofructokinase in kidney of diabetic and normal rats. The activities of these enzymes keep pace with kidney growth, remaining constant per gram tissue but showing a marked increase on the basis of total activity per 100 g body wt. The formation of ¹⁴CO₂ from [1-¹⁴C]glucose and [6-¹⁴C]glucose by kidney slices from diabetic rats was decreased to approximately half the control value; evidence was obtained for an equivalent dilution of the glucose 6-phosphate pool. Correction of the ¹⁴CO₂ yields for the change in specific activity of glucose 6-phosphate yielded values consistent with the enzyme profile. Calculations from specific yields of ¹⁴CO₂ provided evidence for an increased flux of glucose via the pentose phosphate pathway in the kidney in diabetes. The results are discussed in relation to kidney hypertrophy in diabetes and the requirement for ribose 5-phosphate and NADPH for biosynthetic reactions and in relation to the thickening of the basement membrane in diabetes. These results are in accord with the concept of glucose overutilization by non-insulin-requiring tissues.