Use of β-13 C labelled Coniferyl Alcohol to Detect "End-Wise" Polymerization in the Formation of DHPs

Holzforschung ◽  
2000 ◽  
Vol 54 (6) ◽  
pp. 604-608 ◽  
Author(s):  
E. Ämmälahti ◽  
G. Brunow
Keyword(s):  
2D Nmr ◽  
Coniferyl Alcohol ◽  
Template Effect ◽  
Structural Units ◽  
Structural Pattern ◽  
Effect Of Ph ◽  
Coupling Pattern ◽  
Dehydrogenation Polymer

Summary The possibility that preformed dehydrogenation polymer (DHP) could function as a template to induce a structural pattern in DHP more closely resembling that of natural softwood lignin was investigated by oxidizing β-13C-labelled coniferyl alcohol in a medium containing preformed unlabelled polymeric DHP. The experiments were performed at pH 4 and pH 6.5. 1D and 2D NMR were used to estimate the distribution of structural units. No such template effect was found in a comparison of unlabelled with uniformly labelled DHP. Indeed, the effect of pH on the coupling pattern of coniferyl alcohol was greater than the effect of the preformed DHP.

Studies on the dehydrogenative polymerizations of monolignol β-glycosides. Part 2: Horseradish peroxidase-catalyzed dehydrogenative polymerization of isoconiferin

Holzforschung ◽  
2006 ◽  
Vol 60 (5) ◽  
pp. 513-518 ◽  
Author(s):  
Yuki Tobimatsu ◽  
Toshiyuki Takano ◽  
Hiroshi Kamitakahara ◽  
Fumiaki Nakatsubo
Keyword(s):  
Horseradish Peroxidase ◽  
Water Solubility ◽  
Homogeneous System ◽  
Degree Of Polymerization ◽  
Coniferyl Alcohol ◽  
Water Soluble ◽  
Optimum Conditions ◽  
Spectroscopic Analyses ◽  
Dehydrogenation Polymer ◽  
Dehydrogenative Polymerization

Abstract Dehydrogenative polymerization of isoconiferin (IC; coniferyl alcohol γ-O-β-D-glucopyranoside) catalyzed by horseradish peroxidase (HRP) was carried out. The polymerization of IC proceeded in a homogeneous system, resulting in a water-soluble dehydrogenation polymer (IC-DHP). The degree of polymerization (DP) of IC-DHP was significantly higher than that of a standard dehydrogenative polymer (CA-DHP) obtained from coniferyl alcohol (CA) in a heterogeneous system. Under optimum conditions, the DP of IC-DHP was 44 (M n=1.5×104), whereas that for CA-DHP was only 11 (M n=3.0×103, as acetate). Spectroscopic analyses confirmed that IC-DHP has a lignin-like structure containing D-glucose moieties attached to the lignin side-chains. The D-glucose unit introduced into γ-O position of CA essentially influenced the water solubility and molecular mass of the resulting DHP.

scholarly journals Insight into the template effect of vesicles on the laccase-catalyzed oligomerization of N-phenyl-1,4-phenylenediamine from Raman spectroscopy and cyclic voltammetry measurements

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Aleksandra Janoševic Ležaić ◽  
Sandra Luginbühl ◽  
Danica Bajuk-Bogdanović ◽  
Igor Pašti ◽  
Reinhard Kissner ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Cyclic Voltammetry ◽  
Redox Activity ◽  
Salt Form ◽  
Template Effect ◽  
Structural Units ◽  
Redox Active ◽  
First Time ◽  
Insight Into

Abstract We report about the first Raman spectroscopy study of a vesicle-assisted enzyme-catalyzed oligomerization reaction. The aniline dimer N-phenyl-1,4-phenylenediamine (= p-aminodiphenylamine, PADPA) was oxidized and oligomerized with Trametes versicolor laccase and dissolved O2 in the presence of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) vesicles (80–100 nm diameter) as templates. The conversion of PADPA into oligomeric products, poly(PADPA), was monitored during the reaction by in situ Raman spectroscopy. The results obtained are compared with UV/vis/NIR and EPR measurements. All three complementary methods indicate that at least some of the poly(PADPA) products, formed in the presence of AOT vesicles, resemble the conductive emeraldine salt form of polyaniline (PANI-ES). The Raman measurements also show that structural units different from those of “ordinary” PANI-ES are present too. Without vesicles PANI-ES-like products are not obtained. For the first time, the as-prepared stable poly(PADPA)-AOT vesicle suspension was used directly to coat electrodes (without product isolation) for investigating redox activities of poly(PADPA) by cyclic voltammetry (CV). CV showed that poly(PADPA) produced with vesicles is redox active not only at pH 1.1–as expected for PANI-ES–but also at pH 6.0, unlike PANI-ES and poly(PADPA) synthesized without vesicles. This extended pH range of the redox activity of poly(PADPA) is important for applications.

Structural Analysis of Residual and Technical Lignins by 1H-13C Correlation 2D NMR-Spectroscopy

Holzforschung ◽  
2001 ◽  
Vol 55 (3) ◽  
pp. 302-308 ◽  
Author(s):  
Ewellyn A. Capanema ◽  
Mikhail Yu Balakshin ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Hanna Gracz
Keyword(s):  
Structural Analysis ◽  
Eucalyptus Globulus ◽  
2D Nmr ◽  
Kraft Lignin ◽  
Coniferyl Alcohol ◽  
Spectroscopic Techniques ◽  
Carbonyl Groups ◽  
2D Nmr Spectroscopy ◽  
Organosolv Lignin ◽  
Technical Lignins

Summary Structural analysis was conducted on residual lignin from pine Kraft AQ pulp, Eucalyptus Kraft lignin from Eucalyptus globulus and Repap Organosolv lignin by 2D 13C-1H correlation NMR spectroscopic techniques such as HMQC sequence. These lignins contain a rather wide variety of saturated aliphatic groups. The HMQC NMR spectra of the lignins do not verify the presence of diarylmethane moieties in any lignin investigated. The type and amount of other condensed structures depend on the nature of lignin preparation. All the lignins investigated still contained β-O-4′, pino- and syringayresinol (β-β′) and phenylcoumarane (β-5′) structures. Stilbene structures were also identified. Vinyl ether structures were present only in Eucalyptus Kraft lignin. All the lignins contain α-carbonyl groups conjugated to aromatic moieties as terminal side chains rather than involving β-O-4′ structures. No coniferyl alcohol and coniferyl aldehyde type structures are detected in the lignins after pulping. The spectra of kraft lignins show some new signals, the origin of which is discussed.

scholarly journals Clerodendrone, a Novel Hydroquinone Diterpenoid from Clerodendrum Indicum

2003 ◽  
Vol 2003 (7) ◽  
pp. 440-441 ◽  
Author(s):  
N. Ravindranath ◽  
C. Ramesh ◽  
K. Hara Kishore ◽  
U.SN. Murty ◽  
Biswanath Das
Keyword(s):  
Chemical Reactions ◽  
2D Nmr ◽  
Chemical Investigation ◽  
Structural Pattern ◽  
Nmr Data

Chemical investigation of Clerodendrum indicum has resulted in the isolation of clerodendrone, a new member of hydroquinone diterpenoids (which are rare in the investigated family, Verbenaceae). The compound was characterised from its spectral (1D and 2D NMR) data and chemical reactions and was found to contain an uncommon structural pattern with beta-methyl dihydrofuran moiety.

Solid State NMR Analysis of β-13C-Enriched Lignocellulosic Material During Light-Induced Yellowing

Holzforschung ◽  
2001 ◽  
Vol 55 (3) ◽  
pp. 276-282 ◽  
Author(s):  
Jim Parkås ◽  
Magnus Paulsson ◽  
Ulla Westermark ◽  
Noritsugu Terashima
Keyword(s):  
Cell Wall ◽  
Solid State ◽  
Structural Changes ◽  
Coniferyl Alcohol ◽  
Enzymatic System ◽  
Nmr Analysis ◽  
End Groups ◽  
A New Technique ◽  
Dehydrogenation Polymer ◽  
C Nmr

Summary Photoyellowing of lignocellulosic materials has been studied with a new technique based on solid state 13C-NMR analysis of 13C-enriched DHP in cell wall tissue. The selectively 13C-enriched cell wall-dehydrogenation polymer (CW-DHP) was prepared directly on differentiating xylem from spruce (Picea abies) at pH 6.0 by administering β-13C-enriched coniferin in an enzymatic system consisting of glucose oxidase, β-glucosidase, and the naturally occurring water-insoluble enzymes remaining in the cell wall. The bonding pattern of the formed CW-DHP was found to be: 42% β-β, β-5, and β-1 substructures; 36% β-O-4 derived substructures; and 22% coniferyl alcohol and coniferaldehyde end-groups. The 13C-NMR analysis of unirradiated and irradiated tissue revealed a decrease in the relative amount of coniferaldehyde and/or coniferyl alcohol end-groups during irradiation. Prolonged irradiation also introduced new signals centered at 37, 70, and 102 ppm. The results indicate that the present technique, with the formation of DHP in a naturally lignifying carbohydrate environment, has the potential of being a valuable tool for the study of structural changes of lignin during light-induced yellowing.

2D NMR studies on muscle and cerebral metabolism in vivo

1994 ◽  
Vol 91 ◽  
pp. 697-703 ◽  
Author(s):  
B Gillet ◽  
BT Doan ◽  
C Verre-Sebrie ◽  
O Fedeli ◽  
JC Beloeil ◽  
...  
Keyword(s):  
Cerebral Metabolism ◽  
2D Nmr ◽  
Nmr Studies

Histological Study of Human Thyroid Gland Relative Proportion of Parenchyma and Stroma in Thyroid Glands of Bangladeshi People

2013 ◽  
Vol 1 (2) ◽  
pp. 17-20
Author(s):  
Md Enayet Ullah ◽  
Hasna Hena ◽  
Rubina Qasim
Keyword(s):  
Thyroid Gland ◽  
Histological Study ◽  
Relative Proportion ◽  
Age Groups ◽  
Human Thyroid ◽  
Structural Units ◽  
Thyroid Glands ◽  
Group A ◽  
Group B ◽  
Connective Tissue Sheath

Deep cervical fascia forms a connective tissue sheath around the thyroid gland. Delicate trabeculae and septa penetrate the gland indistinctly dividing the gland into lobes and lobules which in turn composed of follicles.1,2,3 These follicles are structural units of thyroid gland which varies greatly in size and shape.4 The number of follicles varies in different age groups. The study was carried out to see the percentage of area occupied by follicles in the stained section of thyroid glands in different age groups. The collected samples were grouped as A (3.5 – 20yrs), B (21- 40yrs) & C (41 – 78yrs). Percentage of area occupied by follicles was (58.55±10.72) in group A, (63.79±12.35) in group B + (63.39±8.29) in group C.DOI: http://dx.doi.org/10.3329/updcj.v1i2.13981 Update Dent. Coll. j. 2011: 1(2): 17-20

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