Oxidative cleavage of lipids with sodium metaperiodate in pyridine

The cleavage of alpha-diols and alpha-amino alcohols with sodium metaperiodate proceeds under mild conditions and in high yields when pyridine is used as reaction medium. The method is suitable for preparative as well as analytical applications.     

The effects of sodium metaperiodate on T and B lymphocytes.

The differential mitogenic response of T and B lymphocytes to sodium metaperiodate has been investigated. It was found that periodate treatment leads to lymphocyte stimulation in spleen cells from Balb/c mice but not in spleen cells from the congenitally athymic nu/nu mice. In addition, treatment of Balb/c spleen cells with anti-θ serum plus complement lowers the mitogenic response to periodate and to concanavalin A without affecting the response to lipopolysaccharide. These results suggest a requirement for the presence of T lymphocytes in the initiation of a response to periodate. Spleen cells from nude mice also react with periodate, and their ability to respond to B cell mitogens is impaired after treatment with the chemical reagent.     

Labeling of soybean agglutinin by oxidation with sodium periodate followed by reduction with sodium [3-H]borohydride.

Periodate oxidation of soybean agglutinin, a glycoprotein lectin, resulted in destruction of up to 5 out of the 9 mannose residues present in each of its subunits (MW 30,000) without any loss of hemagglutinating activity. The oxidation did, however, abolish the interaction of soybean agglutinin with concanvalin A, as measured by quantitative precipitation. Reduction with sodium [3-H]borohydride of soybean agglutinin in which 4 out of 9 mannose residues per subunit were oxidized, afforded a radioactive product which retained full hemagglutinating activity and was indistinguishable from the native lectin by gel filtration, gel electrophoresis, and affinity chromatography. These results establish that the integrity of the carbohydrate side chain of soybean agglutinin is not essential for the biological activity of the lectin, and suggest a general method for the preparation of radioactive glycoprotein lectins.     

Antibiofilm activity of sodium bicarbonate, sodium metaperiodate and SDS combination against dental unit waterline-associated bacteria and yeast

Aim: To determine the effect of sodium bicarbonate (SB), sodium metaperiodate (SMP) and sodium dodecyl sulfate (SDS) combination on biofilm formation and dispersal in dental unit waterline (DUWL)-associated bacteria and yeast. Methods and Results: The in vitro effect of SB, SMP and SDS alone and in combination on biofilm formation and dispersal in Pseudomonas aeruginosa, Klebsiella pneumoniae, Actinomyces naeslundii, and Candida albicans was investigated using a 96-well microtitre plate biofilm assay. The combination showed a broad-spectrum inhibitory effect on growth as well as biofilm formation of both gram-negative and gram-positive bacteria, and yeast. In addition, the SB + SMP + SDS combination was significantly more effective in dispersing biofilm than the individual compounds. The combination dispersed more than 90% of P. aeruginosa biofilm whereas the commercial products, Oxygenal 6, Sterilex Ultra, and PeraSafe showed no biofilm dispersal activity. Conclusion: The composition comprising SB, SMP, and SDS was effective in inhibiting as well as dispersing biofilms in DUWL-associated bacteria and yeast. Significance and Impact of the Study: This study shows that a composition comprising environmentally friendly and biologically safe compounds such as SB, SMP, and SDS has a potential application in reducing DUWL-associated acquired infections in dental clinics.     

Chemical modification of photosystem II core complex pigments with sodium borohydride

The reaction of the irreversible chemical reduction of the 13¹-keto C=O group of pheophytin a (Pheo a) with sodium borohydride in reaction centers (RCs) of functionally active spinach photosystem II (PS II) core complexes was studied. Stable, chromatographically purified PS II core complex preparations with altered chromophore composition are obtained in which ～25% of Pheo a molecules are modified to 13¹-deoxo-13¹-hydroxy-Pheo a. Some of the chlorophyll a molecules in the complexes were also irreversibly reduced with borohydride to 13¹-deoxo-13¹-hydroxy-chlorophyll a. Based on the results of comparative study of spectral, biochemical, and photochemical properties of NaBH₄-treated and control preparations, it was concluded that: (i) the borohydride treatment did not result in significant dissociation of the PS II core complex protein ensemble; (ii) the modified complexes retained the ability to photoaccumulate the radical anion of the pheophytin electron acceptor in the presence of exogenous electron donor; (iii) only the photochemically inactive pheo-phytin Pheo_D2 is subjected to the borohydride treatment; (iv) the Q_x optical transition of the Pheo_D2 molecule in the RC of PS II core complexes is located at 543 nm; (v) in the Q_y spectral region, Pheo_D2 probably absorbs at ～680 nm.     

Stereospecificity of sodium borohydride reduction of tyrosine decarboxylase from Streptococcus faecalis.

Sodium boro[3H]hydride reduction of tyrosine decarboxylase from Streptococcus faecalis followed by complete hydrolysis of the enzyme produces epsilon-[3H]pyridoxyllysine. Degradation of this material to [4'-3H]pyridoxamine and stereochemical analysis with apoaspartate aminotransferase shows that the re side at C-4' of the cofactor is exposed to solvent at pH 5.5 and 7.0. After binding of L-tyrosine at pH 5.5 or tyramine at pH 7.0 to the holoenzyme, sodium boro[3H]hydride reduction proceeds from the si face at C-4' of the substrate . cofactor complex. This indicates one of two conformational changes occurs upon binding of substrate; either rotation about the C-4 to C-4' bond in the cofactor or rotation about the axis through the C-5 and C-5' bond.     

Reduction of autofluorescence on DNA microarrays and slide surfaces by treatment with sodium borohydride

Microarray technology is currently being used extensively in functional genomics research and modern drug discovery and development. Henceforward, tremendous application potential for this technology exists in the fields of clinical diagnostics and prognostics, pathology, and toxicology for high-throughput analysis of "disease" gene expression. However, the major hurdle now in this technology is not the performance of the arrays but rather the efficient reproducibility of the hybridization signal intensity in a fluorescence-based analysis. The sensitivity of fluorescence detection on an array is to a large extent limited by the amount of background signal arising due to nonspecifically bound probes and fluorescence that is intrinsically associated with the chip substrate and/or the attached target DNA, the so-called autofluorescence. Here, we describe a simple and efficient method to reduce autofluorescence from undetermined sources on coated glass slides with and without DNA arrays. This sodium borohydride-mediated reduction process resulted in significantly lower and more even background fluorescence. This in turn extended the dynamic range of detection and reduced the average coefficient of variation of fluorescent signal ratios on DNA microarrays in addition to improving the detection of genes that are expressed at a low level.     

Relative enrichment of P-870 in photosynthetic reaction centers treated with sodium borohydride

Reaction centers from Rhodopseudomonas sphaeroides R26 in 0.03% LDAO/0.1 M Tris (initial pH = 8.0) were treated with sodium borohydride. The pH of the reaction center solution was never allowed to exceed 10. Absorption spectra taken at various times show that for approx. 8 h after the first addition of NaBH₄, A₈₆₅ (P-870) and A₇₆₀ diminish very little (no more than 15% loss each), while A₈₀₀ diminishes markedly (45% loss) and a new peak (at 715 nm) grows in at approximately the same rate that A₈₀₀ decays. Separate experiments on the absorption and ¹H-NMR spectra of purified bacteriochlorophyll (BChl) and bacteriopheophytin (BPh), and their respective NaBH₄-reduction products, reveal that A₇₁₅ in NaBH₄-treated reaction centers most likely results from 2a-deoxy-2a-(hydroxy)BPh a, a BPh reduction product. We conclude that at least part of the BChl contributing to A₈₀₀ in the reaction center is reduced at the acetyl group by NaBH₄, apparently with concomitant pheophytinization; if two molecules of BChl contribute equally to that absorption, one of them is reduced. Thus, it is plausible that, of the 6 bacteriochlorin molecules in the reaction center, only one is so configured that its acetyl group is both accessible to the solvent and reactive. In addition to providing a new geometric marker for reaction centers, the NaBH₄-reduction technique should make it possible to decide whether any small spectral change in the 800-nm region can be ruled out as the higher-energy exciton transition of the putative BChl special pair. The technique should be interesting to apply to reaction centers from other organisms, especially Rhodopseudomonas viridis. Because NaBH₄ treatment is unlikely to significantly modify protein structure, investigations of the photochemical properties of the modified reaction centers should be highly informative, especially since reversible bleaching of P-870 in NaBH₄-treated reaction centers now has been observed (Maroti, P., Wraight, C.A. and Pearlstein, R.M., unpublished results).     

Stereospecificity of sodium borohydride reduction of pig kidney dopa decarboxylase

Sodium boro[3H]hydride reduction of pig kidney 3,4 dihydroxyphenylalanine decarboxylase followed by complete hydrolysis of the enzyme produced epsilon-[3H]pyridoxyllysine. Degradation of this material to 4'-[3H]pyridoxamine and stereochemical analysis with apoaspartate aminotransferase showed that the re side at C-4' of the coenzyme is exposed to solvent. In order to determine the face exposed to the solvent in the external Schiff's base, attempts to trap reaction intermediates were made by reduction with sodium boro [3H]hydride of the holoenzyme in the presence of various substrates or substrate analogs. In all cases, covalently bound radioactive material was found which was identified as epsilon-N-pyridoxyllysine. These results suggest that the internal Schiff's base is in mobile equilibrium with the external Schiff's base and that sodium borohydride reduction displaces this equilibrium, resulting in complete reduction of the internal Schiff's base.     

Identification of the prosthetic group of urocanase. The mode of its reaction with sodium borohydride and of its photochemical reactivation.

Urocanase from Pseudomonas putida and from beef liver were isolated by modifying described procedures. Both enzymes were inactivated and labeled on treatment with tritiated sodium borohydride and gave, upon subsequent hydrolysis, a radioactive acid. The previously reported identity of this acid as 2-hydroxybutanoic acid was disproved by several criteria. Other hydroxy acids were also proved to be different from the radioactive acid derived from urocanase. A large portion of the radioactive material from P. putida was found to be nicotinic acid by 1H NMR spectroscopy, gas-liquid chromatography of its methyl ester, and co-crystallization with authentic reference compounds both as the acid and as the hydrazide. A significant portion of the radioactive material derived from beef liver urocanase also co-crystallized with nicotinic acid. Sodium borohydride-treated inactive urocanase was partially reactivated by light. The action spectrum of the photoreactivation showed a maximum at 330 nm. Treatment of urocanase with sodium borodeuteride followed by hydrolysis afforded a sample of nicotinic acid which carried deuterium mainly in position 6. Both the reversible reducibility of urocanase and its action spectrum of photoreactivation suggest that urocanase contains an enzyme-bound nicotinamide nucleotide molecule which is essential for enzymic activity.