The mode of action of the isolated form of tomato endo-D-galacturonanase

1981 ◽  
Vol 46 (2) ◽  
pp. 525-531
Author(s):  
Oskar Markovič ◽  
Alexander Slezárik
Keyword(s):  
Molecular Weight ◽  
Binding Site ◽  
Chain Length ◽  
Mode Of Action ◽  
Aldehyde Group ◽  
Polymerization Degree ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The mode of action of the isolated form of tomato endo-D-galacturonanase of molecular weight close to 50 000 was investigated with oligo-D-galactosiduronic acids of polymerization degree 2-7 and their derivatives the terminal aldehyde group of which was reduced. The rate of hydrolysis, catalysed by this enzyme decreased with the shortening the chain length of oligo-D-galactosiduronates used; di(D-galactosiduronic) acid was not hydrolyzed by this enzyme at all. Tri(D-galactosiduronic) acid was cleaved into monomer and dimer, tetra(D-galactosiduronic) acid was alternatively cleaved into monomer and trimer, as well as into two dimers. The previously proposed conception that the binding site of the tomato endo-D-galacturonanase contains three subsites and that the catalytic groups are localized close to the first bond from the reducing end of the substrate segment bound in the complex were proved. The mode of hydrolysis of the reduced oligomers is in favour of the mentioned conception.

Influence of chain length on the rate of hydrolysis of polyoxymethylene ethers

1972 ◽  
Vol 16 (6) ◽  
pp. 1447-1456 ◽  
Author(s):  
David J. Stanonis ◽  
Walter D. King ◽  
Sidney L. Vail
Keyword(s):  
Chain Length ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

scholarly journals Substrate specificity and mode of action of a cellulase from Aspergillus niger

1978 ◽  
Vol 169 (2) ◽  
pp. 389-395 ◽  
Author(s):  
P L Hurst ◽  
P A Sullivan ◽  
M G Shepherd
Keyword(s):  
Aspergillus Niger ◽  
Substrate Specificity ◽  
Mode Of Action ◽  
Cellulose Derivatives ◽  
Polygalacturonic Acid ◽  
Glycol Chitosan ◽  
Glucose Polymer ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Low Activity

The mode of action and substrate specificity of a cellulase purified from Aspergillus niger were examined. The enzyme showed little capacity to hydrolyse highly ordered cellulose, but readily attacked soluble cellulose derivatives and amorphous alkali-swollen cellulose. Activity towards barley glucan and lichenin was greater than with CM-cellulose. Low activity was detected with CM-pachyman (a substituted beta-1,3-glucose polymer) and xylan. Activity towards yeast glucan, mannan, ethlene glycol chitin, glycol chitosan, laminarin, polygalacturonic acid and pectin could not be demonstrated. Cellobiose and p-nitrophenyl beta-D-glucoside were not hydrolysed, whereas the rate of hydrolysis of the higher members of the reduced cellulodextrins increased with chain length. The central bonds of cellotetraosylsorbitol and cellopentaosylsorbitol were the preferred points of clevage. Kinetic data indicated that the specificity region of the cellulase is five glucose units in length. The evidence indicates that the cellulase is an endoglucanase.

scholarly journals Nucleotide sequences of similar size from the coliphage R17 genome

1973 ◽  
Vol 131 (3) ◽  
pp. 605-610 ◽  
Author(s):  
Ulrich F. E. Rensing ◽  
Alan Coulson ◽  
E. O. P. Thompson
Keyword(s):  
Molecular Weight ◽  
Coat Protein ◽  
Binding Site ◽  
Chain Length ◽  
Secondary Structures ◽  
Nucleotide Sequences ◽  
Ribosome Binding Site ◽  
Ribosome Binding ◽  
Loop Region ◽  
Main Component

A sequence of 33 nucleotides from the coliphage R17 RNA genome was determined. It constitutes the main component of a mixture of fragments that migrate together on electrophoresis in a separation according to molecular weight. Fragments of comparable chain length from 3′ end of RNA from coliphage R17, from a region preceding and overlapping the coat-protein cistron ribosome binding site and from the beginning of the A-protein cistron, were also found and characterized. ‘Hairpin’-like secondary structures are proposed for the longer fragments, one of which appears to have a tetranucleotide excised in the loop region.

Intestinal Absorption of Stereoisomers of Dipeptides in the Rat

1973 ◽  
Vol 45 (2) ◽  
pp. 199-212 ◽  
Author(s):  
A. M. Asatoor ◽  
Amrit Chadha ◽  
M. D. Milne ◽  
D. I. Prosser
Keyword(s):  
Molecular Weight ◽  
Intestinal Mucosa ◽  
Inverse Correlation ◽  
Rat Jejunum ◽  
Stomach Tube ◽  
Jejunal Absorption ◽  
Rate Of Hydrolysis ◽  
Diffusion Mechanisms ◽  
Hydrolysis Of

1. Studies have been made of jejunal absorption rates in vivo in the rat of the stereoisomers of alanylphenylalanine, leucyl-leucine and glycyltryptophan. Absorption rates of l-alanyl-l-phenylalanine were about 200 times those of d-alanyl-d-phenylalanine, l-leucyl-l-leucine about 24 times those of the dd-isomer, and glycyl-l-tryptophan 5 times those of glycyl-d-tryptophan. The mixed ld- and ld-isomers were absorbed at intermediate rates. 2. Absorption rates were positively correlated with the rate of hydrolysis of each dipeptide by homogenates of rat intestinal mucosa. The transport rate and rate of hydrolysis of glycyl-d-tryptophan, d-alanyl-d-phenylalanine and d-leucyl-d-leucine were significantly greater in the ileum than in the jejunum. 3. When given by stomach tube the most slowly absorbed dipeptides, d-alanyl-d- phenylalanine, d-leucyl-d-leucine and glycyl-d-tryptophan were the only ones to be excreted in significant amounts in the urine, showing that they were absorbed as the entire molecule and were resistant to hydrolysis by tissue peptidases. 4. There was a close inverse correlation between the rates of transport by rat jejunum of glycine, d-alanine, d-leucine, d-phenylalanine, d-tryptophan, d-alanyl-d- phenylalanine, d-leucyl-d-leucine and glycyl-d-tryptophan and the molecular weight of each compound, suggesting that diffusion mechanisms play an appreciable part in jejunal absorption of these compounds. No such correlation was found in the case of the ileum.

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

Polarographic study of hydrolysis of [8-lysine]vasopressin and its derivatives with blood serum of pregnant women

1980 ◽  
Vol 45 (4) ◽  
pp. 1099-1108 ◽  
Author(s):  
Mikuláš Chavko ◽  
Michal Bartík ◽  
Evžen Kasafírek
Keyword(s):  
Blood Serum ◽  
Pregnant Women ◽  
Degree Of Hydrolysis ◽  
Polarographic Study ◽  
Ph Optimum ◽  
Lysine Vasopressin ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Vasopressin Analogues

A polarographic study of the hydrolysis of [8-lysine]vasopressin and some hormonogens of the vasopressin series with the blood serum of women in the last week of pregnancy was studied. The dependence of hydrolysis on pH (pH optimum: 7.4-7.50, substrate concentration (Km 1.2 . 10-5M), pH stability and thermal stability were determined. The rate of hydrolysis of individual vasopressin analogues decreases in the order: [8-lysine]vasopressin > Nα-glycyl-prolyl[8-lysine]-vasopressin > Nα-leucyl-[8-lysine]vasopressin > Nα-alanyl-[8-lysine]vasopressin > Nα-phenyl alanyl-[8-lysine]vasopressin > Nα-diglycyl-[8-lysine]vasopressin > Nα-prolyl-[8-lysine]vasopressin > Nα-triglycyl-[8-lysine]vasopressin > Nα-sarcosyl-glycyl-[8-lysine]vasopressin. The degree of hydrolysis gradually increases to a multiple with the length of the pregnancy in consequence of the presence of oxytocine. However, vasopressin is also hydrolysed to a small extent with the enzymes from the blood sera of non-pregnant women. Under similar analytical conditions oxytocin was not hydrolysed with the sera of non-pregnant women and therefore oxytocin is a more suitable substrate than vasopressin for polarographic determination of serum oxytocinase.

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