scholarly journals Polarimetry and 13C n.m.r. show that the hydrolyses of β-d-glucopyranosyl fluoride by β(1→3)-glucanases from Phanerochaete chrysosporium and Sporotrichum dimorphosporum have opposite stereochemistries

1993 ◽  
Vol 293 (2) ◽  
pp. 591-594 ◽  
Author(s):  
J L Copa-Patiño ◽  
Y Zhang ◽  
B Padmaperuma ◽  
I Marsden ◽  
P Broda ◽  
...  
Keyword(s):  
Phanerochaete Chrysosporium ◽  
Optical Rotation ◽  
Fluoride Ion ◽  
Ion Release ◽  
Unpublished Work ◽  
Time Courses ◽  
Hydrolysis Of ◽  
Proton Decoupling

The time courses of optical rotation and fluoride ion release during hydrolysis of beta-D-glucopyranosyl fluoride by the beta(1-->3)-glucanase of Phanerochaete chrysosporium (J. L. Copa-Patiño and P. Broda, unpublished work) indicated that the initial sugar product was beta-D-glucopyranose. This was confirmed by monitoring the hydrolysis of 1-[13C]beta-D-glucopyranosyl fluoride by this enzyme with 13C n.m.r. (without proton decoupling). The same two techniques were used to confirm that hydrolysis of beta-D-glucopyranosyl fluoride by the exo beta(-->3)-glucanase of ‘Basidiomycete QM 806’ (identified as Sporotrichum dimorphosporum) yielded alpha-glucopyranose as first sugar product, in accordance with previous results using laminarin as substrate [Parrish and Reese (1963) Carbohydr. Res. 3, 424-429; Nelson (1970) J. Biol. Chem. 245, 869-872].

scholarly journals Hydrolyses of α- and β-cellobiosyl fluorides by cellobiohydrolases of Trichoderma reesei

1993 ◽  
Vol 291 (3) ◽  
pp. 883-888 ◽  
Author(s):  
A K Konstantinidis ◽  
I Marsden ◽  
M L Sinnott
Keyword(s):  
Trichoderma Reesei ◽  
Biological Function ◽  
Fluoride Ion ◽  
Cellobiohydrolase I ◽  
Ion Release ◽  
Cellulase Complex ◽  
Cellobiohydrolase Ii ◽  
Glycoside Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Cellobiohydrolase II hydrolyses alpha- and beta-D-cellobiosyl fluorides to alpha-cellobiose at comparable rates, according to Michaelis-Menten kinetics. The stereochemistry, absence of transfer products and strict hyperbolic kinetics of the hydrolysis of alpha-cellobiosyl fluoride suggest that the mechanism for the alpha-fluoride may be the enzymic counterpart of the SNi reaction observed in the trifluoroethanolysis of alpha-glucopyranosyl fluoride [Sinnott and Jencks (1980) J. Am. Chem. Soc. 102, 2026-2032]. The absolute factors by which this enzyme accelerates fluoride ion release are small and greater for the alpha-fluoride than for the beta, suggesting that its biological function may not be just glycoside hydrolysis. Cellobiohydrolase I hydrolyses only beta-cellobiosyl fluoride, which is, however, an approx. 1-3% contaminant in alpha-cellobiosyl fluoride as prepared and purified by conventional methods. Instrumental assays for the various components of the cellulase complex are discussed.

scholarly journals Effects of Powdery Cellulose Nanofiber Addition on the Properties of Glass Ionomer Cement

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3077 ◽  
Author(s):  
Takako Nishimura ◽  
Yukari Shinonaga ◽  
Chikoto Nagaishi ◽  
Rie Imataki ◽  
Michiko Takemura ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Cellulose Nanofibers ◽  
Glass Ionomer Cement ◽  
Chemical Properties ◽  
Fluoride Ion ◽  
Strength Testing ◽  
Glass Ionomer ◽  
Ion Release ◽  
Diametral Tensile Strength ◽  
Ionomer Cement

In this study, we aimed to evaluate the effect of the addition of powdery cellulose nanofibers (CNFs) on the mechanical properties of glass ionomer cement (GIC) without negatively affecting its chemical properties. Commercial GIC was reinforced with powdery CNFs (2–8 wt.%) and characterized in terms of flexural strength, compressive strength, diametral tensile strength, and fluoride-ion release properties. Powdery CNFs and samples subjected to flexural strength testing were observed via scanning electron microscopy. CNF incorporation was found to significantly improve the flexural, compressive, and diametral tensile strengths of GIC, and the corresponding composite was shown to contain fibrillar aggregates of nanofibers interspersed in the GIC matrix. No significant differences in fluoride-ion release properties were observed between the control GIC and the CNF-GIC composite. Thus, powdery CNFs were concluded to be a promising GIC reinforcement agent.

scholarly journals Mechanical and Functional Properties of a Novel Apatite-Ionomer Cement for Prevention and Remineralization of Dental Caries

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3998 ◽  
Author(s):  
Rie Imataki ◽  
Yukari Shinonaga ◽  
Takako Nishimura ◽  
Yoko Abe ◽  
Kenji Arita
Keyword(s):  
Fracture Toughness ◽  
Functional Properties ◽  
Glass Ionomer Cement ◽  
Pediatric Dentistry ◽  
Cement Matrix ◽  
Fluoride Ion ◽  
Ion Release ◽  
Fluoride Ions ◽  
Acid Buffer ◽  
Ionomer Cement

Especially in pediatric dentistry, prevention by the control of initial lesions prior to cavitation is very important, and application of a pit and fissure sealant is essential to achieve this. Numerous reports have suggested that resin-based sealants are inferior to sealants based on glass-ionomer cement (GIC), because of GIC’s many advantages, such as fluoride ion release properties and its good adhesion to tooth structures. However, the use of GIC is impeded due to its low flexural strength and fracture toughness. In this paper, we developed and characterized an apatite-ionomer cement (AIC) that incorporates hydroxyapatite (HAp) into the GIC; this development was aimed at not only reinforcing the flexural and compressive strength but also improving some functional properties for the creation of the material suitable for sealant. We examined the influence of differences in the compounding conditions of GIC powder, liquid, and HAp on flexural and compressive strengths, fracture toughness, fluoride ion release property, shear bond strength to bovine enamel, surface pH of setting cements, and acid buffer capability. These methods were aimed at elucidating the reaction mechanism of porous spherical-shaped HAp (HApS) in AIC. The following observations were deduced. (1) HAp can improve the mechanical strengths of AIC by strengthening the cement matrix. (2) The functional properties of AIC, such as acid buffer capability, improved by increasing the releasing amounts of various ions including fluoride ions. The novel AIC developed in this study is a clinically effective dental material for prevention and remineralization of tooth and initial carious lesion.

scholarly journals THE INTERRELATION OF THE SURVIVING HEART AND PANCREAS OF THE DOG IN SUGAR METABOLISM

1917 ◽  
Vol 26 (5) ◽  
pp. 721-744 ◽  
Author(s):  
Admont H. Clark
Keyword(s):  
Optical Rotation ◽  
Reducing Power ◽  
Sugar Metabolism ◽  
Weak Acid ◽  
Perfused Pancreas ◽  
Melting Points ◽  
Optical Rotations ◽  
Normal Utilization ◽  
Hydrolysis Of ◽  
Reducing Properties

When the pancreas of a dog is perfused aseptically with a Locke's solution containing dextrose in physiological concentrations, the optical rotation of the perfusate is diminished, but its reducing power is unaltered. This change also occurs if dextrose is added to a sugarfree pancreatic perfusate and the mixture incubated. These perfusates yield osazones with lower melting points than glucosazone, but when the perfusates are hydrolyzed with weak acid their optical, rotations and the melting points of their osazones are increased. These changes do not occur with levulose, or with an extract of the pancreas and dextrose. When the heart, spleen, or kidneys are perfused with dextrose solutions hydrolysis of the perfusates does not increase their optical rotation or power of reduction. When a pancreatic perfusate containing dextrose is circulated through a living heart not only do the above changes take place but, in addition, the reducing properties of the perfusate are altered. Hydrolysis of such a perfusate increases its reducing power, its optical rotation, and the melting point of its osazone. A heart does not cause this effect either alone or when perfused together with the spleen or kidneys. Levulose perfused through the heart and pancreas is unchanged. These phenomena are believed to be due to an enzyme or enzymes obtained from the perfused pancreas. The changes in optical rotation, in reduction, and in the osazones are accounted for by different degrees of dextrose condensation. While the living heart can destroy both dextrose and levulose to some extent, the experimental results suggest that the enzyme or enzymes derived from the perfused pancreas have a specific action on dextrose and are responsible for certain essential steps by which dextrose is prepared for normal utilization.

scholarly journals Chemical and physical properties of an arabinogalactan-peptide from wheat endosperm

1974 ◽  
Vol 139 (3) ◽  
pp. 535-545 ◽  
Author(s):  
G. B. Fincher ◽  
W. H. Sawyer ◽  
B. A. Stone
Keyword(s):  
Optical Rotation ◽  
Subcellular Location ◽  
Successive Treatment ◽  
Partial Acid Hydrolysis ◽  
Wheat Endosperm ◽  
Anomeric Configuration ◽  
Molecular Core ◽  
Tentative Model ◽  
And Function ◽  
Hydrolysis Of

1. An arabinogalactan-peptide from wheat endosperm was studied by using physicochemical techniques and some aspects of its chemical structure were determined. 2. The arabinogalactan-peptide is a non-associating, polydisperse macromolecule ([unk]=22000) which exhibits only minor non-ideal effects in aqueous solution. 3. Examination of the products of partial acid hydrolysis of the polysaccharide component showed that arabinose is present in the α-l-arabinofuranosyl configuration, and i.r.-absorption spectroscopy and optical-rotation studies suggest that the d-galactopyranose residues are linked by glycosidic linkages in the β-anomeric configuration. 4. The arabinogalactan is linked to a peptide which represents 8% (w/w) of the arabinogalactan-peptide and which may be present as a molecular core. Partial degradation of the polymer by successive treatment with oxalic acid and NaOH showed that the linkage between polysaccharide and peptide involves galactose and hydroxyproline residues and is glycosidic in nature. A tentative model is proposed for the structure of the wheat endosperm arabinogalactan-peptide. 5. The subcellular location and function of the arabinogalactan-peptide is discussed in relation to previous work with related molecules.

scholarly journals Hatsusamides A and B: Two New Metabolites Produced by the Deep-Sea-Derived Fungal Strain Penicillium steckii FKJ-0213

Marine Drugs ◽  
2020 ◽  
Vol 18 (10) ◽  
pp. 513
Author(s):  
Hirotaka Matsuo ◽  
Rei Hokari ◽  
Aki Ishiyama ◽  
Masato Iwatsuki ◽  
Mayuka Higo ◽  
...  
Keyword(s):  
Optical Rotation ◽  
Hybrid Structure ◽  
Culture Broth ◽  
Nmr Data ◽  
1H Nuclear Magnetic Resonance ◽  
Ic50 Values ◽  
Hela S3 ◽  
Hydrolysis Of ◽  
Fcr3 Strain ◽  
New Metabolites

Two new nitrogen-containing metabolites, designated hatsusamide A (1) and B (2), were isolated from a culture broth of Penicilliumsteckii FKJ-0213 together with the known compounds tanzawaic acid B (3) and trichodermamide C (4) by physicochemical (PC) screening. The structures of 1 and 2 were determined as a tanzawaic acid B-trichodermamide C hybrid structure and a new analog of aspergillazines, respectively. The absolute configuration of 1 was determined by comparing the values of tanzawaic acid B and trichodermamide C in the literatures, such as 1H-nuclear magnetic resonance (1H-NMR) data and optical rotation, after hydrolysis of 1. Compounds 1–4 were evaluated for cytotoxicity and anti-malarial activities. Compounds 1 and 3 exhibited weak anti-malarial activity at half-maximal inhibitory concentration (IC50) values of 27.2 and 78.5 µM against the K1 strain, and 27.9 and 79.2 µM against the FCR3 strain of Plasmodium falciparum, respectively. Furthermore, 1 exhibited cytotoxicity against HeLa S3, A549, Panc1, HT29 and H1299 cells, with IC50 values of 15.0, 13.7, 12.9, 6.8, and 18.7 μM, respectively.

THE PREPARATION OF L-α-GLYCERYLPHOSPHORYLCHOLINE FROM LECITHINS

1955 ◽  
Vol 33 (5) ◽  
pp. 761-766 ◽  
Author(s):  
N. H. Tattrie ◽  
C. S. McArthur
Keyword(s):  
Cadmium Chloride ◽  
Inorganic Salt ◽  
Optical Rotation ◽  
Chloride Complex ◽  
Ion Exchange Resins ◽  
Aqueous Alcohol ◽  
Synthetic Compound ◽  
Exchange Resins ◽  
Hydrolysis Of ◽  
Crude Lecithin

Investigation of the hydrolysis of phosphatidylcholines (lecithins) in hot aqueous alcohol under the influence of mercuric chloride has shown that glycerylphosphorylcholine is formed and that neither racemization nor migration of the phosphorylcholine moiety occurs. The fatty acids are split off much more rapidly than is choline and as a consequence appreciable amounts of glycerylphosphorylcholine are formed. On the basis of these observations a procedure was devised for the hydrolysis of crude lecithin and the isolation of glycerylphosphorylcholine in a yield of 69%. The product was identified as L-α-glycerylphosphorylcholine by analysis of its cadmium chloride complex, and comparison of its optical rotation with that of the synthetic compound of known configuration. Recovery of the diester from this complex was accomplished through removal of the inorganic salt by ion-exchange resins and the free L-α-glycerylphosphorylcholine was crystallized from 99% ethanol.

ChemInform Abstract: Solid Phase Peptide Synthesis: Fluoride Ion Release of Protected Peptide Fragments.

ChemInform ◽  
2010 ◽  
Vol 23 (19) ◽  
pp. no-no
Author(s):  
R. RAMAGE ◽  
C. A. BARRON ◽  
S. BIELECKI ◽  
R. HOLDEN ◽  
D. W. THOMAS
Keyword(s):  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Fluoride Ion ◽  
Peptide Fragments ◽  
Ion Release

ChemInform Abstract: Solid Phase Peptide Synthesis: Fluoride Ion Release of Peptide from the Resin.

ChemInform ◽  
1988 ◽  
Vol 19 (6) ◽  
Author(s):  
R. RAMAGE ◽  
C. A. BARRON ◽  
S. BIELECKI ◽  
D. W. THOMAS
Keyword(s):  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Fluoride Ion ◽  
Ion Release
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