scholarly journals Chemically modified nylons as supports for enzyme immobilization. Polyisonitrile-nylon

1974 ◽  
Vol 143 (3) ◽  
pp. 497-509 ◽  
Author(s):  
Leon Goldstein ◽  
Amihay Freeman ◽  
Mordechai Sokolovsky
Keyword(s):  
Aqueous Medium ◽  
Enzyme Immobilization ◽  
Functional Group ◽  
Carboxyl Groups ◽  
Partial Hydrolysis ◽  
Amino Groups ◽  
Tyrosine Residues ◽  
Chemically Modified ◽  
Reactive Groups ◽  
Hydrolysis Of

Four-component condensations between amine, carboxyl, isocyanide and aldehyde lead to the formation of N-substituted amides (Ugi, 1962). The present paper describes the use of such condensations for the introduction of chemically reactive groups on to the polyamide backbone of nylon. Polyisonitrile-nylon was synthesized by partial hydrolysis of nylon-6 powder, followed by resealing of the newly formed −CO2... NH2− pairs via a four-component condensation, by using acetaldehyde and 1,6-di-isocyanohexane. Polyisonitrile-nylon could also be converted into a diazotizable arylamino derivative, polyaminoaryl-nylon, by a four-component condensation by using a bifunctional amine, pp′-diaminodiphenylmethane, in the presence of an aldehyde and a carboxylate compound. The versatility of four-component condensations involving the isocyanide functional group of polyisonitrile-nylon allowed coupling of proteins, in an aqueous medium at neutral pH, through either their amino or carboxyl groups. Trypsin and papain were bound to polyisonitrile-nylon through their amino groups by a four-component condensation by using acetaldehyde and acetate; conversely, succinyl-(3-carboxypropionyl-)trypsin, pepsin and papain were coupled through their carboxyl groups in the presence of acetaldehyde and an amine (Tris). Diazotized polyaminoaryl-nylon could be utilized for the immobilization of papain, via the tyrosine residues of the enzyme.

scholarly journals Relationship between isoelectric point of native and chemically modified insulin and liposomal fusion

1989 ◽  
Vol 264 (1) ◽  
pp. 285-287 ◽  
Author(s):  
R N Farías ◽  
A E López Viñals ◽  
E Posse ◽  
R D Morero
Keyword(s):  
Methyl Ester ◽  
Isoelectric Point ◽  
Carboxyl Groups ◽  
Amino Groups ◽  
Chemically Modified ◽  
Glycine Methyl Ester ◽  
Native Insulin ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Fusion Ability

Native insulin causes fusion of negatively charged liposomes in the pH range from 3.0 to 5.5. In marked contrast, insulin with all three amino groups succinylated did not show fusion ability at any pH. On the other hand, insulin amidated with glycine methyl ester with all six carboxyl groups blocked shifted its activity to higher pH, showing a pH range of activity from 3.0 to 7.4. When the carboxyl groups were recovered by hydrolysis of methoxyl groups from glycine methyl ester-treated insulin, the protein obtained (glycyl-insulin with six free carboxyl groups) behaved as native insulin. A good correlation between the isoelectric point values of insulin and its derivatives and their fusion properties was found.

Kinetics of the Reaction of Nitrous Acid with Model Compounds and Proteins, and the Conformational State of N-terminal Groups in the Chymotrypsin Family

1972 ◽  
Vol 50 (12) ◽  
pp. 1282-1296 ◽  
Author(s):  
A. Kurosky ◽  
T. Hofmann
Keyword(s):  
Nitrous Acid ◽  
Conformational State ◽  
Serine Proteinases ◽  
Amino Groups ◽  
Model Compounds ◽  
Third Order ◽  
Tyrosine Residues ◽  
Reactive Groups ◽  
Primary Amino ◽  
Kinetics Of

The kinetics of the reaction of nitrous acid at 4° and pH 4.0 with various amino acids, peptides, and proteins were studied. The reaction with isoleucine methyl ester was found to have a linear dependence on the square of the HONO concentration showing that N2O3 was the reactive species. Third order nitrosation rate constants of primary amino groups showed a correlation with their pK values. They were calculated for the concentration of the unprotonated species to give intrinsic reactivities. The rate of nitrosation of acetyltryptophan to give N-nitrosoacetyltryptophan was found to be a linear function of the nitrous acid concentration. This nitrosation therefore follows a different mechanism. The reaction of nitrous acid with tyrosine residues was examined by spectrophotometry. The reaction was negligible compared to that of other groups. Acetylhistidine and imidazole did not react. Reactivities for α-amino groups, ε-amino groups, and other residues in proteins were compared. The conformational state of the N-terminal residues in serine proteinases, as revealed from their reactivities, is discussed in detail. It is concluded that nitrous acid reacts preferentially with "surface" residues and is a useful tool for exploring conformational states of reactive groups in proteins, especially α-amino groups and indole rings.

scholarly journals Inhitive ability collagenase of N-(cinnamyl) chitooligosaccharide derivative

2017 ◽  
Vol 20 (K3) ◽  
pp. 83-91
Author(s):  
Xuan Minh Le ◽  
Khanh Duy Nguyen ◽  
Khoa Dang Tran ◽  
Tuan Quoc Tran ◽  
Nghiep Dai Ngo
Keyword(s):  
Molecular Weight ◽  
Room Temperature ◽  
Positive Control ◽  
Living Systems ◽  
Amino Groups ◽  
Animal Cells ◽  
Chemically Modified ◽  
Mtt Method ◽  
Hydrolysis Of ◽  
Derivatives Of

Chitooligosaccharides (COS) with molecular weight 4633 Da and 84.67% of deacetylation were synthesized by hydrolysis of chitosan by cellulase at room temperature (33 ± 1 ° C). This COS, then, were chemically modified by grafting cinnamaldehyde at amino groups on the COS. Derivatives of N- (cinnamyl) chitooligosaccharides (CCOS) synthesized with 50.64% of yield and 72.22% of extent of substitution had inhibitory activity enzyme collagenase (a group of matrix metalloproteinases, enzyme family related to metastatic ability of cancer). Compared with the positive control, 58.23% of the effective to inhibit collagenase of CCOS at 1000 μg/ml concentrate. In addition, the CCOS cytotoxicity of CCOS was also assessed by MTT method, the results showed that non-toxic derivatives of animal cells and thus can be tested and applied in living systems.

Distribution of substituent groups in O-(2-aminoethyl)cellulose

1969 ◽  
Vol 47 (9) ◽  
pp. 1571-1580 ◽  
Author(s):  
E. J. Roberts ◽  
S. P. Rowland
Keyword(s):  
Liquid Chromatography ◽  
Functional Group ◽  
Direct Analysis ◽  
Hydroxyl Groups ◽  
Gas Liquid Chromatography ◽  
Amino Groups ◽  
Substantial Fraction ◽  
Chemically Modified ◽  
Amine Function ◽  
Modified Cellulose

O-(2-Aminoethyl)cellulose (degree of substitution 0.14), prepared by reaction of sodium 2-aminoethyl sulfate with cotton fabric, was hydrolyzed to glucose and mono-O-(2-aminoethyl)-D-glucopyranoses which were identified by gas–liquid chromatography (g.l.c.). Complications arise from reactions between the functional group at C-1 of the glucose unit and the amine function of a substituent. The distribution of 2-aminoethyl substituents in the 3-O- and 6-O-positions of the D-glucopyranosyl units of cotton cellulose was estimated to be 0.20:1.00 from direct analysis of the hydrolyzate of O-(2-aminoethyl)cellulose, but the total substitution in the 2-O-position could not be estimated in this manner. The ratio of substituents in the 2-O-, 3-O-, and 6-O-positions was found to be 0.64:0.14:1.00 when the amino groups were converted to hydroxyl groups by diazotization, and the distribution was estimated in terms of the 2-hydroxyethyl substituents. It has been observed that a substantial fraction (57.5%) of the 2-O-(2-hydroxyethyl)-D-glucose from the chemically modified cellulose exists in the form of the inner glucosides. Several new monosubstituted glucoses have been prepared and characterized by g.l.c. for this purpose.

scholarly journals Reaktion des Orthovanadinsäure-tri-tert-butylesters mit Monocarbonsäuren / Reaction of Tris-tert-butylorthovanadate with Monocarboxylic Acids

1979 ◽  
Vol 34 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Fritz Preuss ◽  
Joachim Woitschach
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Chemical Reactions ◽  
Carboxyl Groups ◽  
Partial Hydrolysis ◽  
Bidentate Ligands ◽  
Monocarboxylic Acids ◽  
H Nmr ◽  
Hydrolysis Of

Abstract Tris-tert-butylorthovanadate VO(OC4H9)3 undergoes reaction with monocarboxylic acids to yield monomeric VO(OC4H9)(RCOO)2; no VO(OC4H9)2(RCOO) or VO(RCOO)3 could be isolated from the reaction mixture. Polymeric dioxovanadium(V)-monocarbox-ylates(VO2RCOO)n are formed by thermolysis or partial hydrolysis of VO(OC4H9)(RCOO)2; the reaction mechanism is studied and discussed. Syntheses of Ba[VO2(CH3COO)3], Ba[VO2(C2H5COO)3] and N(C4H9)4[V4O8Br(CH3COO)4] are described. All compounds obtained are characterized by IR and 1H NMR spectroscopy as well as by chemical reactions. The carboxyl groups are mostly acting as bidentate ligands.

Organic material dissolved during oxygen-alkali pulping of hot water extracted birch sawdust

TAPPI Journal ◽  
2015 ◽  
Vol 14 (4) ◽  
pp. 237-244 ◽  
Author(s):  
JONI LEHTO ◽  
RAIMO ALÉN
Keyword(s):  
Acetic Acid ◽  
Betula Pendula ◽  
Cooking Time ◽  
Hot Water ◽  
Partial Hydrolysis ◽  
Chemical Pulping ◽  
Black Liquors ◽  
Aliphatic Carboxylic Acids ◽  
Hydrolysis Of ◽  
Cooking Conditions

Untreated and hot water-treated birch (Betula pendula) sawdust were cooked by the oxygen-alkali method under the same cooking conditions (temperature = 170°C, liquor-to-wood ratio = 5 L/kg, and 19% sodium hydroxide charge on the ovendry sawdust). The pretreatment of feedstock clearly facilitated delignification. After a cooking time of 90 min, the kappa numbers were 47.6 for the untreated birch and 10.3 for the hot water-treated birch. Additionally, the amounts of hydroxy acids in black liquors based on the pretreated sawdust were higher (19.5-22.5g/L) than those in the untreated sawdust black liquors (14.8-15.5 g/L). In contrast, in the former case, the amounts of acetic acid were lower in the pretreated sawdust (13.3-14.8 g/L vs. 16.9-19.1 g/L) because the partial hydrolysis of the acetyl groups in xylan already took place during the hot water extraction of feedstock. The sulfur-free fractions in the pretreatment hydrolysates (mainly carbohydrates and acetic acid) and in black liquors (mainly lignin and aliphatic carboxylic acids) were considered as attractive novel byproducts of chemical pulping.

scholarly journals Magnetic Resonance and Catalytic Studies of Pyruvate Kinase with Essential Sulfhydryl or Lysyl ε-Amino Groups Chemically Modified

1973 ◽  
Vol 248 (10) ◽  
pp. 3419-3425
Author(s):  
Michael Flashner ◽  
Ilana Tamir ◽  
Albert S. Mildvan ◽  
H. Paul Meloche ◽  
Minor J. Coon
Keyword(s):  
Magnetic Resonance ◽  
Pyruvate Kinase ◽  
Amino Groups ◽  
Chemically Modified
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