Molecular symmetry of glyceraldehyde-3-phosphate dehydrogenase from Bacillus coagulans

The thermolabile glyceraldehyde-3-phosphate dehydrogenase from the facultative thermophile Bacillus coagulans has a crystallographically exact 2-fold rotation axis of symmetry in one of its orthorhombic crystal forms (Lee et al., 1982). Using various crystallographic techniques, we have now identified this axis to be the molecular R-axis, which is the symmetry axis that relates the two subunits that form each active site of the tetrameric enzyme. This is in contrast to the symmetry of the human skeletal muscle enzyme wherein the crystallographically exact axis was found to be the Q-axis (Buehner et al., 1974). This finding could have important implications for the possible mechanism for the allosteric behavior of this molecule.

Growth performance and intestinal transit time of rats fed purified and natural dietary fibers

The effects of some selected purified fibers were compared to those derived from cereals or legume seeds. Rats were fed for at least 9 weeks and measurements were taken to determine feed consumption, weight gain, feed efficiency ratios (FER), protein efficiency ratios (PER), apparent protein digestibility, and rate of transit through the gastrointestinal tract. Most diets were designed to contain approximately 10% dietary fiber and 10% protein. Compared to the fiber-free diet, pectin reduced weight gain, FER, PER and apparent protein digestibility values. Cellulose, xylan and raffinose had no influence on feed intake, weight gains or FERs. However, cellulose and xylan increased PER values and the rates of food passage but decreased the apparent protein digestibility values. Feed utilization, protein digestibility and growth were similar for the wheat bran, corn bran and fiber-free diets. These cereal fibers caused the rates of transit to be significantly increased relative to the fiber-free control diet. The hull and cell-wall-fiber fractions of beans, when compared to the fiber-free diet, had little effect on feed consumption, growth, FER or PER. The cell-wall-fiber fraction reduced apparent protein digestibility and the hull fraction accelerated food passage relative to the fiber-free diet.

Calculation of volume fluctuation for globular protein models

The extent of volume fluctuation is calculated for two simple geometrical models of globular protein molecules subjected to a potential that is proportional to the surface area freshly generated by the thermal breathing motion. The proportionality constant, gamma, has the unit of surface tension. The calculated values are compared with estimates made from the compressibility measurements. After an approximate correction for the hydration effect, the experimental values are found to be between those calculated by using gamma values of 25 and 46 cal/mol/A2 (1 cal = 4.184 J). These values bracket previously reported independent estimates of interfacial tension that presumably operates at the interface between a nonpolar molecule and water. This result appears to indicate that the solvent water plays a significant role in determining the extent of volume fluctuation of globular proteins and that the concept, and the actual value of the estimate, of the interfacial tension around a nonpolar molecule in water may, in fact, be useful in some applications.

Pediatric colonoscopy

With the improvement of instruments, colonoscopy has become applicable also for children. During the past 10 years, pediatric colonoscopies were performed 83 times on 45 infants and children. The value and indications in pediatric colonoscopy are described here. Pediatric colonoscopy is a very significant complement to the conventional clinical and radiologic examinations.

Investigation of the influence of progesterone on mouse embryo transport by using antiprogestational steroids

The rate of embryo transport through the mouse oviduct was unaltered by ovariectomy after ovulation, essentially unaltered by administration of progesterone after ovulation but increased by preovulatory administration of progesterone. The antiprogestational steroid RMI 12,936 caused an arrest of embryo movement when given on Day 1, 2 or 3 of pregnancy and similar, though less marked, delay was caused by R2323, another progesterone antagonist. The effects of RMI 12,936 given on Day 1 were reversed by progesterone administration after a latent period of 24-48 h. These results indicate that the egg transport process in the mouse in triggered by progesterone and requires continued progesterone activity for its maintenance.

The effect of reserpine, oestradiol and in-vitro perfusion on oviduct calcium levels in the mouse during egg transport

Mouse oviduct calcium content, determined by atomic absorbance after ashing of the tissue, showed a significant fall on Day 2 of pregnancy followed by a significant rise on Day 3. This pattern was altered by administration of reserpine and oestradiol in doses which were shown to alter the rate of egg transport. In-vitro perfusion of the oviduct, capable of maintaining muscular activity and back and forth movement of eggs for 24 h, was associated with lack of forward progressive motion of eggs and by a more rapid increase in tissue calcium levels during incubation than occurred in vivo.

Food and Drug Administration's adverse drug reaction monitoring program

The adverse drug reaction monitoring program of the Division of Drug Experience within the FDA is described. Historical information on the development and activities of the current drug reaction monitoring program, and goals and objectives of the current program are discussed. Also presented are a brief description of the Voluntary Reporting System, intensive drug monitoring studies and special epidemiologic studies, and a workable definition of alert reports and examples of their previous role within the FDA. Pharmacists should participate actively in adverse drug reaction monitoring.

Xeroderma pigmentosum fibroblasts of the D group lack an apurinic DNA endonuclease species with a low apparent Km

Apurinic DNA endonuclease activity from cultured human fibroblasts was resolved into two species by phosphocellulose chromatography. The species had sedimentation coefficients of 3.3 S and 2.8 S and apparent Km's for apurinic sites of 5 and 44 nM, respectively. The low Km species was absent from extracts of cell lines XP5BE, XP6BE and XP7BE of xeroderma pigmentosum complementation group D.

Human uracil DNA N-glycosidase: studies in normal and repair defective cultured fibroblasts

Uracil DNA N-glycosidase, an enzyme which participates in the excision of uracil from DNA, was measured in extracts from fibroblasts lines cultured from normal subjects, from several subjects with the genetic disease xeroderma pigmentosum, and from a subject with ataxia telangiectasia. The cell lines representative of complementation groups A and D of xeroderma pigmentosum and of ataxia telangiectasia had roughly the same level of activity as did the normal cells. On the other hand, cells from two xeroderma pigmentosum variants (XP4BE and XP13BE) had roughly half the normal level of activity, and cells from the heterozygous mother of XP4BE had an intermediate level of activity. In spite of these quantitative differences, no systematic alterations in reaction characteristics, apparent Km for substrate, or purification characteristics were noted for enzyme from any of the lines. Thus a causal relationship, if any, between levels of activity and the disease symptoms is equivocal.

Crystallographic studies on L-asparaginase from Proteus vulgaris. II. Symmetry and location of the tetrameric molecule

Analyses of the x-ray diffraction intensity data by the Patterson synthesis and rotation function techniques show that the true space group of the monoclinic crystals of L-asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1) from Proteus vulgaris is P21, that the molecular centers lie at x = 0.054, y = 0, z = 0.256, and its symmetry related positions, and that the tetramer molecules possess three approximate, mutually perpendicular 2-fold rotational symmetries, the axes of which run along the directions of the crystallographic a*-, b-, and c-axes. In addition, an investigation of the molecular packing arrangement in the crystal indicates that the tetramer molecules possess an approximately regular tetrahedral subunit structure.