Integrating Separation and Conversion—Conversion of Biorefinery Process Streams to Biobased Chemicals and Fuels

The concept of the integrated biorefinery is critical to developing a robust biorefining industry in the USA. Within this model, the biorefinery will produce fuel as a high-volume output addressing domestic energy needs and biobased chemical products (high-value organics) as an output providing necessary economic support for fuel production. This paper will overview recent developments within two aspects of the integrated biorefinery—the fractionation of biomass into individual process streams and the subsequent conversion of lignin into chemical products. Solvent-based separation of switchgrass, poplar, and mixed feedstocks is being developed as a biorefinery “front end” and will be described as a function of fractionation conditions. Control over the properties and structure of the individual biomass components (carbohydrates and lignin) can be observed by adjusting the fractionation process. Subsequent conversion of the lignin isolated from this fractionation leads to low molecular weight aromatics from selective chemical oxidation. Together, processes such as these provide examples of foundational technology that will contribute to a robust domestic biorefining industry.     

Conversion of d-Glucose into d-Oxybiotin†

2,5-Anhydro-3-azido-3-deoxy-D-xylose dimethyl acetal (XI), the key intermediate for the stereospecific synthesis of d-oxybiotin, was prepared by methanolysis of 3-azido-3-deoxy-1,2-O-isopropylidene-5-O-p-tolylsulfonyl-α-d-xylofuranose (VIIIa) or of 3-azido-3-deoxy-l,2-O-cyclohexylidene-5-0-p-tolylsulfonyl-α-d-xylofuranose (VIIIb).     

Conversion ofN-acetyl-o-toluidine into 4′-hydroxy-N-acetyl-o-toluidine byFusarium verticillioides

Summary Approximately 850 fungus and yeast strains were tested for their ability to hydroxylateN-acetyl-o-toluidine in the 4-position. The strain Y-1 selected as the best producer, was identified asFusarium verticilliides, and accumulated 1.5 mg of 4-hydroxy-N-acetyl-o-toluidine per ml of culture broth.     

Conversion of α-Terpineol to 8,9-Epoxy-p-menthan-1-ol

The complete amino acid sequence of pokeweed lectin-B (PL-B) has been analyzed by first sequencing seven lysylendopeptidase peptides derived from the reduced and S-pyridylethylated PL-B and then connecting them by analyzing the arginylendopeptidase peptides from the reduced and S-carboxymethylated PL-B. PL-B consists of 295 amino acid residues and two oligosaccharides linked to Asn96 and Asnl39, and has a molecular mass of 34,493 Da. PL-B is composed of seven repetitive chitin-binding domains having 48–79% sequence homology with each other. Twelve amino acid residues including eight cysteine residues in these domains are absolutely conserved in all other chitin-binding domains of plant lectins and class I chitinases. Also, it was strongly suggested that the extremely high hemagglutinating and mitogenic activities of PL-B may be ascribed to its seven-domain structure.     

Polymorphism and Gene Conversion in Mouse α-Globin Haplotypes

We have cloned and characterized three distinct alpha-globin haplotypes obtained from inbred strains of the mouse, Mus domesticus. We report here the complete nucleotide sequence of the six alpha-globin genes that the haplotypes contain. Our analysis of these genes and those from one other previously described haplotype indicates that recurrent gene conversion events have played a major role in their history. The pattern of nucleotide substitutions suggests that conversions have occurred both within and between haplotypes. Limited segments of coding and noncoding DNA have been involved in these gene conversion events. In two of the haplotypes, the nonallelic genes of each maintain DNA sequence identity over discrete intervals and encode the same alpha-globin polypeptide. On the other hand, the coding regions of some genes have accumulated replacement changes that result in distinct alpha-globins. In one instance, these changes appear to reflect positive selection of advantageous mutations.     

Conversion of Methylthioadenosine Into its Naturally Occurring 3′-Isomer

Abstract

Methylthioadenosine (MTA) has been converted into its 3′ naturally occurring isomer (xylosyl-MTA) via protection at 2′-OH, oxidation, reduction and deprotection.     

Effects of Pyrazinamide on Tryptophan–Niacin Conversion in Rats

In the course of our screening for a new anti-tumor substance, the bisabolane sesquiterpenoid endoperoxide, 3,6-epidioxy-1,10-bisaboladiene (EDBD), was isolated from the edible wild-plant, Cacalia delphiniifolia. EDBD showed cytotoxicity toward human chronic myelogenous leukemia K562 and human prostate carcinoma LNCaP cell lines with IC₅₀ values of 9.1 μM and 23.4 μM, respectively. DNA fragmentation and condensation of chromatin, the hallmarks of apoptosis, appeared in K562 cells after an 18-h treatment with EDBD. α-Curcumene, a bisabolane sesquiterpene that lacks the endoperoxide moiety of EDBD, also showed cytotoxicity toward both K562 and LNCaP cell lines at over a 10-times higher dose than that of EDBD. The results indicate the importance of the endoperoxide structure within EDBD to its anti-tumor activity in vitro.     

Conversion of cellobiose to glucose using immobilized β-glucosidase reactors

Cellobiose is an intermediate in the enzymatic hydrolysis of cellulose to glucose and acts as an inhibitor for the cellulase enzymes. The conversion of cellobiose to glucose was studied with β-glucosidase adsorbed on Amberlite DP-1, a cation-exchange resin. The best overall pH for adsorption and reactor operation was near 5.0. The K_m values increased with increasing enzyme loading due to competitive inhibition. The maximum practical enzyme loading was about 28 units/g resin. The immobilized enzyme was operated continously in both packed bed and fluidized bed reactors, giving half-lives between 200 and 375 h.     

Conversion of 5′-inosinic acid to inosine by Streptomyces aureus

The production of inosine by microbial conversion of 5′-inosinic acid (IMP) was investigated. Among the various strains of Streptomyces and Bacillus tested, Streptomyces aureus NCIB 9803 was selected for the microbial conversion process due to its high IMP-degrading activity. A maximum conversion yield of 0.43 (86% of the theoretical value) was obtained when IMP was added to the culture medium at 24 h. Kinetic studies with [8-¹⁴C] IMP showed that the difference from the theoretical values mainly attributable to the uptake of inosine by S. aureus.     

Gene Conversion and Functional Divergence in the β-Globin Gene Family

Different models of gene family evolution have been proposed to explain the mechanism whereby gene copies created by gene duplications are maintained and diverge in function. Ohta proposed a model which predicts a burst of nonsynonymous substitutions following gene duplication and the preservation of duplicates through positive selection. An alternative model, the duplication–degeneration–complementation (DDC) model, does not explicitly require the action of positive Darwinian selection for the maintenance of duplicated gene copies, although purifying selection is assumed to continue to act on both copies. A potential outcome of the DDC model is heterogeneity in purifying selection among the gene copies, due to partitioning of subfunctions which complement each other. By using the d_N/d_S () rate ratio to measure selection pressure, we can distinguish between these two very different evolutionary scenarios. In this study we investigated these scenarios in the -globin family of genes, a textbook example of evolution by gene duplication. We assembled a comprehensive dataset of 72 vertebrate -globin sequences. The estimated phylogeny suggested multiple gene duplication and gene conversion events. By using different programs to detect recombination, we confirmed several cases of gene conversion and detected two new cases. We tested evolutionary scenarios derived from Ohtas model and the DDC model by examining selective pressures along lineages in a phylogeny of -globin genes in eutherian mammals. We did not find significant evidence for an increase in the ratio following major duplication events in this family. However, one exception to this pattern was the duplication of -globin in simian primates, after which a few sites were identified to be under positive selection. Overall, our results suggest that following gene duplications, paralogous copies of -globin genes evolved under a nonepisodic process of functional divergence.[Reviewing Editor: Martin Kreitman]     

Tubercidin: Its Conversion to 5′-Amino-5′-deoxytubercidin

A method for the determination of allethrin and other pesticides in mosquito coils was developed by the combination of shaking extraction and gas chromatography (GC). Allethrin and other pesticides were adequately extracted by shaking for only half an hour with a mixture of toluene and 99% formic acid (5:1). This shaking extraction method was more effective for shortening the extraction time compared with the Soxhlet extraction method, and accurate determination was achieved without the interference from inert materials in the mosquito coils. The recovery of allethrin in various contents from the coils was 96.6 to 97.1%, with a 1.2 to 1.5% coefficient of variation. Furthermore, the recoveries of other pesticides and synergists from the coils were 94 to 102% by this shaking extraction method.     

EGCG Inhibited Lipofuscin Formation Based on Intercepting Amyloidogenic β-Sheet-Rich Structure Conversion

Background

Lipofuscin (LF) is formed during lipid peroxidation and sugar glycosylation by carbonyl-amino crosslinks with biomacrolecules, and accumulates slowly within postmitotic cells. The environmental pollution, modern dietary culture and lifestyle changes have been found to be the major sources of reactive carbonyl compounds in vivo. Irreversible carbonyl-amino crosslinks induced by carbonyl stress are essentially toxiferous for aging-related functional losses in modern society. Results show that (-)-epigallocatechin gallate (EGCG), the main polyphenol in green tea, can neutralize the carbonyl-amino cross-linking reaction and inhibit LF formation, but the underlying mechanism is unknown.

Methods and Results

We explored the mechanism of the neutralization process from protein, cell, and animal levels using spectrofluorometry, infrared spectroscopy, conformation antibodies, and electron microscopy. LF demonstrated an amyloidogenic β-sheet-rich with antiparallel structure, which accelerated the carbonyl-amino crosslinks formation and disrupted proteolysis in both PC12 cells and D-galactose (D-gal)-induced brain aging mice models. Additionally, EGCG effectively inhibited the formation of the amyloidogenic β-sheet-rich structure of LF, and prevented its conversion into toxic and on-pathway aggregation intermediates, thereby cutting off the carbonyl-amino crosslinks.

Conclusions

Our study indicated that the amyloidogenic β-sheet structure of LF may be the core driving force for carbonyl-amino crosslinks further formation, which mediates the formation of amyloid fibrils from native state of biomacrolecules. That EGCG exhibits anti-amyloidogenic β-sheet-rich structure properties to prevent the LF formation represents a novel strategy to impede the development of degenerative processes caused by ageing or stress-induced premature senescence in modern environments.     

Synthesis and Photochemical Conversion of Oligonucleotides Containing 2-Chloro-2′-Deoxyadenosine

Abstract

The rate and velocity of the photoconversion of 2-chloro-2′-deoxyadenosine into 2′-deoxyisoguanosine within oligonucleotides was found to be sequence-specific and depends on the nearest neighbor.     

Chemical Conversion of Some Ribonucleosides into the Corresponding β-D-Arabinofuranosyl Derivatives1

Abstract

Five 3′,5′-di-O-acylribonucleosides were converted into the corresponding β-D-arabinofuranosyl derivatives through DMSO-oxidation followed by NaBH₄-reduction and deacylation with NaOMe-MeOH.     

Conversion of Orotic Acid to Uridine-5′-monophosphate by Enzymes of Micrococcus glutamicus

An enzyme system which could convert orotic acid to uridine-5′-monophosphate (5′-UMP) was found in cell-free extract of a threonine-requiring auxotroph of Micrococcus glutamicus (Syn. Corynebacterium glutamicum) 534 Co-147. This reaction required 5-phosphoribosylpyrophosphate (PRPP) and magnesium ion as essential components. The product of the enzyme reaction was separated by ion exchange resin chromatography and identified to be uridine-5′-monopbosphate. From the stoichiometric studies and other characteristics, it became evident that this enzyme reaction proceeded according to the following equation and was assumed to be catalyzed by orotidine-5′-monophosphate pyrophosphorylase and orotidine-5′-monophosphate decarboxylase. $\text{Orotic}\text{ acid + PRPP}\underset{{\text{Mg}}^{++}}{\to }{5}^{\prime }?\text{UMP}+\text{PPi}+{\text{CO}}_2$     

Critical Main-Chain Length for Conformational Conversion From 310-Helix to α-Helix in Polypeptides

Abstract

To assess the minimal peptide length required for the stabilization of the a-helix relative to the 3₁₀-helix in Aib-rich peptides, we have solved the X-ray diffraction structures of the terminally blocked sequential hexa- and octapeptides with the general formula -(Aib-L-Ala)_n-(n = 3 and 4, respectively). The hexapeptide molecules are completely 3₁₀-helical with four 1 ← 4 intramolecular N-H … O=C H-bonds. On the other hand, the octapeptide molecules are essentially α-helical with four 1 ← 5 H-bonds; however, the helix is elongated at the N-terminus, with two 1 ← 4 H-bonds, giving these molecules a mixed α/3₁₀-helical character. In both compounds the right-handed screw sense of the helix is dictated by the presence of the Ala residues of L-configuration. This study represents the first experimental proof for a 3₁₀ →α-helix conversion in the crystal state induced by peptide backbone lengthening only.     

Solar Selective Absorbers for High-efficiency Photothermal Conversion via Core–Shell Nanocone Structured Surface

Nanostructured surface, a promising photon management strategy, enables to enhance photon-to-heat conversion efficiency by manipulating spectral radiative properties ranging from solar spectrum (0.3–2.5 μm) to mid-infrared spectrum (2.5–20 μm). Here, a core–shell nanocone structured surface made of silica core and tungsten shell as a solar selective absorber is introduced. The photothermal conversion efficiency (PTCE) is calculated in consideration of solar spectrum absorption and mid-infrared emission. It is obvious that high solar spectrum absorption and low mid-infrared emission are beneficial for high PTCE. The influence of structural parameters on the PTCE is studied, and then the absorption enhancement mechanism is elucidated in detail. Meanwhile, the influences of incident angle, polarized state, and lattice arrangement are also presented. The calculated results exhibit that our optimized solar absorber possesses the total solar absorption of 97.3% and total thermal emission of 7.6%, resulting in a maximum PTCE of 91.4% under one sun illumination conditions at normal incidence. Moreover, our solar selective absorber is independent to the incident angle and polarization state. The excellent photothermal conversion performance with wide-angle and polarization-insensitive properties for the solar selective absorber can serve as a good candidate for various solar thermal applications including seawater desalination, steam generation, thermophotovoltaic, and photocatalysis.