C.P.-D.D.-M.A.S. 13C-N.M.R. investigations of anhydrous and hydrated cyclomalto-oligosaccharides: The role of water of hydration

Hydrated and anhydrous cyclomaltohexaose, cyclomaltoheptaose, and cyclomalto-octaose (cyclodextrins) have been investigated by the c.p.-d.d.-m.a.s. ¹³C-n.m.r. technique. The chemical shifts of the signals of C-1 and C-6 provide information about conformation and the results agree fairly well with the earlier scattering data on hydrated systems, but some discrepancies have been found for cyclomaltohexaose. Th conformation of the macro-rings seems to be determined by the hydration water. The unique role of water in forming crystals of cyclomalto-oligosaccharides is demonstrated.     

Proteinases of Streptomyces fradiae. II. Specificity.

It has been shown that extracellular proteinases synthesized by a keratinolytic strain of S. fradiae are characterized by diversified activity in the decomposition of both proteins and synthetic substrates. Among the six proteinases isolated, apart from the ones dominating and having relatively low specificity, there are two enzymes characterized by narrow catalytic abilities--extremely similar to those of trypsin. These proteinases intensively degraded all the trypsin substrates studied, but they were inactive or showed slight activity toward others. They were also highly sensitive to such specific inhibitors of trypsin as TLCK, SBTI and TIO.     

Metabolism of monofluorobenzoates by Acinetobacter calcoaceticus N.C.I.B. 8250. Formation of monofluorocatechols.

None of the monofluorobenzoates serves as sole source of carbon and energy for growth of Acinetobacter calcoaceticus but all can contribute to growth on other substrates. The monofluorobenzoates are oxidised by bacteria pre-induced for benzoate oxidation and can themselves induce the appropriate enzymes. The initial products of oxidation have been separated and identified by gas-liquid chromatography. 2-Flurobenzoate is oxidised to catechol, fluoride and 3-fluorocatechol; 3-fluorobenzoate gives 3- and 4-fluorocatechol; 4-fluorobenzoate gives 4-fluorocatechol. The fluorocatechols appear to be partially oxidised beyond the stage of 3-oxoadipate by suitably pre-induced bacteria.     

C.P.-M.A.S. 13C-N.M.R. study of some solid-state inclusion complexes of cyclomalto-oligosaccharides with para-substituted benzenes

Cross polarisation—magic-angle sample spinning ¹³C-n.m.r. spectral have been measured in the solid state for p-nitrophenol, p-iodophenol, and their inclusion complexes with cyclomaltohexaose, cyclomaltoheptaose, and methylated cyclomaltohexaose. Analysis of the line-shapes of the resonances and the dipolar-dephasing experiments indicate that the guest molecules undergo motion in the host cavities, whereas the host molecules are almost static. The mode and rate of guest motion depend on the size of the cavity.     

13C-n.m.r. study of C hordein.

Insoluble xylan was prepared from ground birch (Betula pubescens) pulp by alkali extraction and precipitation with ethanol. The only sugar detected after acid hydrolysis of the preparation was xylose. The insoluble xylan was used as substrate in a nephelometric assay to determine the xylanase (EC 3.2.1.8, 1,4-beta-D-xylan xylanohydrolase and EC 3.2.1.37, 1,4-beta-D-xylan xylohydrolase) activities of Aspergillus and Trichoderma enzymes. The nephelometric method is reliable in evaluating xylanase hydrolysis of insoluble xylan.     

R.b.e. and o.e.r. of extended-Bragg-peak helium ions: survival and development of rat embryos.

Rats were exposed under aerobic or hypoxic conditions to 200-1200 rads of 60Co gamma-rays or extended-Bragg-peak helium ions on the eighth day of gestation. Uterine contents were examined on the twentieth day of gestation. At the 50 per cent embryonic survival level, helium ion r.b.e. was 1(.0) (aerobic) and 1(.2) (hypoxic). Maximum attainable gamma-ray and helium-ion o.e.r.s. were 2(.2) and 1(.7) respectively, indicating an oxygen-effect gain (o.e.g.) of 1(.2). At the 10 per cent survival level helium ion r.b.e. was 1(.1) (aerobic) and 1(.4) (hypoxic). Gamma-ray and helium-ion 0.e.r.s. were 2(.0) and 1(.5) respectively, indicating a helium ion o.e.g. of 1(.3). These data demonstrate that the small fraction of high-LET radiation present in this helium ion beam has a neglible effect on the aerobic r.b.e., but lowers the effective o.e.r. of the beam approximately 25 per cent relative to that of gamma-rays. Helium ions were significantly more effective than gamma-rays in killing embryos under hypoxic conditions, in producing congenital abnormalities under aerobic conditions, and in stunting foetal growth under both conditions.     

13C-n.m.r. analysis of some sulphate derivatives of chitosan.

Positions of substitution with sulphate in three water-soluble sulphated derivatives of chitosan were analysed by 13C n.m.r. The structures of N-acetylchitosan 3,6-O-disulphate, sodium chitosan N-, 6-O-disulphate, and sodium chitosan 6-O-monosulphate were confirmed.     

E.s.r. of spin-trapped radicals in aqueous solutions of peptides. Reactions of the hydroxyl radical.

The reactions of hydroxyl radicals with 30 dipeptides and several larger peptides were studied in aqueous solutions. The OH radicals were generated by U.V. photolysis of H2O2. The short-lived peptide radicals were spin-trapped using t-nitrosobutane and identified by e.s.r. For dipeptides containing the amino terminal residues glycine, alanine and phenylalanine, abstraction of the hydrogen from the carbon adjacent to the peptide nitrogen was the major process leading to the spin-adducts. Such radicals will be referred to as backbone radicals. Dipeptides with a carbonyl terminal serine residue and also glycylglutamic acid form both backbone and side-chain radicals, with the latter being formed in larger quantities. For dipeptides, side-chain radicals were detected on either the carboxyl or amino terminal residues of both. The effect of pD on the e.s.r. sectrum of the spin-adducts of glycylglycine was studied and the pK of the carboxyl group of this radical was determined to be 2.5. For (Ala)3 and (Ala)n, with an average value of n = 1800, backbone and minor side-chain radicals were observed. For ribonucleases-S-peptide, containing 20 amino acid residues, both backbone and side-chain radicals were detected.     

1H n.m.r. studies of insulin. Assignment of resonances and properties of tyrosine residues.

The assignment of the aromatic 1H n.m.r. resonances of the four tyrosine residues of bovine 2-zinc insulin is reported, based on double resonance techniques, use of Hahn spin echo pulse sequences and examination of specific derivatives nitrated at tyrosines A14 and A19 as well as des-(B26-B30)-insulin. Titration curves of the four tyrosine residues show that residues A14 and B16 have normal pK' values of 10.3-10.6 in solution, consistent with their accessibility to solvent in monomer and dimer in the crystal. Tyrosine residues A19 and B26 have pK' values of 11.4 and exhibit other features in their titration curves that are consistent with limited accessibility to solvent and a nonpolar environment. The meta protons of residues B16 and B26 both observe the titration of a nearby tyrosine residue, probably A19. Interpretation of the n.m.r. data obtained in solution is consistent with the crystallographic data for the monomer and dimer obtained on insulin crystals [Blundell, Dodson, Hodgkin & Mercola (1972) Adv. Protein Chem. 26, 279-402].     

XXXIV.–Notices of recent Ornithological Publications. An A. B. C. of Common Birds.

[An A. B. C. of Common Birds. A pocket guide to the commoner inland Birds of Britain. Pp. 1–04. Price 6d., by post 7d. Published by the Royal Society for the Protection of Birds, 23 Queen Anne's Gate, S.W.]     

The degradation of cholic acid by Pseudomonas sp. N.C.I.B. 10590.

The microbial degradation of cholic acid by Pseudomonas sp. N.C.I.B. 10590 was studied, and two major products were isolated and identified as 7 alpha, 12 beta-dihydroxyandrosta-1,4-diene-3,17-dione and 7 alpha, 12 alpha-dihydroxy-3-oxopregna-1,4-diene-20-carboxylic acid. Four minor products were isolated and evidence is given for the following structures: 7 alpha, 12 alpha-dihydroxyandrosta-1,4-diene-3,17-dione, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 7 alpha, 12 beta, 17 beta-trihydroxyandrosta-1,4-dien-3-one and 7 alpha, 12 alpha-dihydroxy-3-oxopregn-4-ene-20-carboxylic acid. The significance of the production of the steroid products is discussed, along with the possible enzymic mechanisms responsible for their production.     

Brachyptera Group. Sp.32. C. Brachyptera. Sp.33. C.c RUFA. Sp.34. C. Troglodytes. Sp.35. C. Fulvicapilla.

A part from considerations as to where it is best wedged into the linear sequence, the brachyptera group is defined in general terms as a compact group of four small or very small species which resemble one another in many important specific characters and the other thirty-six species classified here as Cisticola in so many ways of form, coloration and behaviour as to make them best understood by classifying them also under that generic name.     

G.L.C.-M.S. of partially methylated and acetylated derivatives of 3-deoxyoctitols

Partially methylated and acetylated 3-deoxyoctitols were prepared from derivatives of 3-deoxy-d-manno-2-octulosonic acid (KDO), and identified as the d-glycero-d-talo and d-glycero-d-galacto isomers by g.l.c.-m.s. Mono- and oligosaccharide derivatives of KDO were subjected in sequence to methylation, carboxyl-reduction, hydrolysis, carbonyl-reduction, and acetylation to yield 1,2,6-tri-O-acetyl-3-deoxyoctitol derivatives. Carboxyl-reduction and then methylation gave the series of 2,6-di-O-acetyl derivatives. Oligosaccharides with KDO at the reducing end, e.g., β-d-ribofuranosyl-(1→7)-KDO, α-l-glycero-d-manno-heptopyranosyl-(1→5)-KDO, and α-KDOp-(2→4)-KDO, yielded, after carbonyl-reduction, methylation, carboxyl-reduction, hydrolysis, and acetylation, the 1,7-, 1,5-, and 1,4-di-O-acetyl derivatives, whereas remethylation after carboxyl-reduction gave the 7-, 5-, and 4-O-acetyl derivatives of 3-deoxyoctitol. General rules for the fragmentation of 3-deoxyoctitols during e.i.-m.s. were established.     

Neurobiology of Stomotoca. I. Action systems.

The layout of nerves, muscles, and conducting epithelia is described for the simple hydrozoan medusa Stomotoca. Comparisons are drawn with Sarsia and other recently studied forms. The major action systems are those responsible for swimming, crumpling (protective involution), tentacle posture, pointing (unilateral reciprocal flexions of the manubrium and margin), and visceral movements (barely mentioned). Crumpling is a simple summating response in this species. Crumpling and pointing are considered to use the same effectors but different conduction pathways. New histological results include the demonstration of a nerve plexus running through the endodermal canal system and a nerve plexus in the ectoderm encircling the peduncle. Special attention is given to the distribution of synapses and gap junctions, as possible trasmission pathways in behavioral responses. Some details are included on organization within the marginal nerve rings.     

Aspects of audit. 1. The background.

Methods of reviewing health care already exist in Britain, but the debate continues about how practical and acceptable such a review is. The many different terms used to describe review only confuse the issue. "Audit" is a useful term for describing the review of medical work by medical people. This can be divided into "internal audit," or peer review, and "external audit"--that is, review by organisations outside hospital and general practice. The concepts of internal and external audit have a great impact upon the attitudes held by the medical profession about audit. The shortcomings of audit by the professional standards review organisations in the United States are not inevitable in Britian.     

Studies of polysaccharide fractions from the lipopolysaccharide of Pseudomonas aeruginosa N.C.T.C. 1999.

Two polymeric water-soluble fractions were isolated by gel filtration after mild acid hydrolysis of the lipopolysaccharide from Pseudomonas aeruginosa N.C.T.C. 1999. The fraction of higher molecular weight retained the O-antigenic specificity of the lipopolysaccharide and may be 'side-chain' material. This fraction was rich in N (about 10%) and gave several basic amino compounds on acid hydrolysis; fucosamine (at least 2.8% w/w) was the only specifc component identified. The fraction of lower molecular weight was a phosphorylated polysaccharide apparently corresponding to 'core' material. The major components of this fraction and their approximate molar proportions were: glucose (3-4); rhamnose (1); heptose (2); 3-deoxy-2-octulonic acid (1); galactosamine (1); alanine (1-1.5); phosphorus (6-7). In the intact lipopolysaccharide this fraction was probably linked to lipid A via a second residue of 3-deoxy-2-octulonic acid, and probably also contained additional phosphate residues and ethanolamine. The residues of 3-deoxy-2-octulonic acid were apparently substituted in the C-4 or C-5 position, and the phosphorylated heptose residues in the C-3 position. The rhamnose was mainly 2-substituted, though a little 3-substitution was detected. The glucose residues were either unsubstituted or 6-substituted. Four neutral oligosaccharides were produced by partial acid hydrolysis and were characterized by chemical, enzymic, chromatographic and mass-spectrometric methods of analysis. The structures assigned were: Glcpalpha1-6Glc; Glcpbeta1-2Rha; Rhapalpha1-6Glc; Glcpbeta1-2Rhapalpha1-6Glc. The galactosamine was substituted in the C-3 or C-4 position, the attachment of alanine was indicated, and evidence that the amino sugar linked the glucose-rhamnose region to the 'inner core' was obtained.     

Kinetics of rouleau formation. II. Reversible reactions.

Red blood cells aggregate face-to-face to form long, cylindrical, straight chains and sometimes branched structures called rouleaux. Here we extend a kinetic model developed by R. W. Samsel and A. S. Perelson (1982, Biophys. J. 37:493-514) to include both the formation and dissociation of rouleaux. We examine thermodynamic constraints on the rate constants of the model imposed by the principle of detailed balance. Incorporation of reverse reactions allows us to compute mean sizes of rouleaux and straight chain segments within rouleaux, as functions of time and at equilibrium. Using the Flory - Stockmayer method from polymer chemistry, we obtain a closed-form solution for the size distribution of straight chain segments within rouleaux at any point in the evolution of the reaction. The predictions of our theory compare favorably with data collected by D. Kernick , A.W.L. Jay , S. Rowlands , and L. Skibo (1973, Can. J. Physiol. Pharmacol. 51:690-699) on the kinetics of rouleau formation. When rouleaux grow large, they may contain rings or loops and take on the appearance of a network. We demonstrate the importance of including the kinetics of ring closure in the development of realistic models of rouleaux formation.