Effect of Nε-Alkylation of the Substrate on the Hydrolysis of Benzoylglycyl-L-Lysine by Carboxypeptidase B

1975 ◽  
Vol 53 (11) ◽  
pp. 1145-1149 ◽  
Author(s):  
Graham J. Moore ◽  
N. Leo Benoiton
Keyword(s):  
Aqueous Solution ◽  
Steric Hindrance ◽  
Alkyl Group ◽  
Side Chain ◽  
Methyl Ethyl ◽  
Reductive Methylation ◽  
Carboxypeptidase B ◽  
Substrate Side ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The action of carboxypeptidase B (EC 3.4.12.3) on the benzoylglycyl dipeptides Bz-Gly-Lys(X) where X = methyl, ethyl, propyl, formyl, dimethyl, isopropyl, trimethyl, and benzyl has been investigated. All were hydrolyzed, at a rate decreasing in the order indicated, except where X = trimethyl and benzyl. Compounds where X = dimethyl, formyl, and isopropyl were hydrolyzed very slowly, and did not inhibit the hydrolysis of Bz-Gly-Lys by the enzyme. The kinetic parameters kcat and Km were determined for compounds with X = methyl and ethyl. The observed decrease in rate of hydrolysis of substrates with increasing size of X is consistent with increasing steric hindrance effects arising from the interaction of the Nε-alkyl group with residues of the protein in the cleft which accommodates the substrate side-chain, and resulting in weaker binding of the substrate.Bz-Gly-Lys(Me2) was prepared by reductive methylation of Bz-Gly-Lys. Bz-Gly-Lys(Me3) was prepared by the reaction of Bz-Gly-Lys(Me2) with diazomethane in aqueous solution. Bz-Gly-Lys(Me) and Bz-Gly-Lys(Et) were synthesized by classical coupling procedures from the appropriately protected lysine derivatives.

THE CHEMISTRY OF ETHYLENE OXIDE: V. THE REACTION OF ETHYLENE OXIDE WITH HALIDE IONS IN NEUTRAL AND ACID SOLUTION

1952 ◽  
Vol 30 (3) ◽  
pp. 169-176 ◽  
Author(s):  
A. M. Eastham ◽  
G. A. Latremouille
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Acid Solution ◽  
Activation Energies ◽  
Hydrogen Halide ◽  
Halide Ions ◽  
Neutral Aqueous Solution ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The rates of reaction of halide ions with ethylene oxide in neutral aqueous solution and the rate of hydrolysis of ethylene oxide in acid solution have been measured and the activation energies determined. From these data and from the ratio of glycol to chlorohydrin formed when ethylene oxide reacts with excess aqueous hydrogen halide, the rates of the acid-catalyzed addition of halide ions to ethylene oxide at 25 °C. have been estimated.

Lanthanum ion catalysis of nucleophilic displacement reactions of monoesters of methyl phosphonic acid

1969 ◽  
Vol 47 (23) ◽  
pp. 4383-4387 ◽  
Author(s):  
R. J. Withey
Keyword(s):  
Aqueous Solution ◽  
Phosphonic Acid ◽  
Methylphosphonic Acid ◽  
Nucleophilic Displacement ◽  
Displacement Reactions ◽  
Lanthanum Ion ◽  
Rate Of Hydrolysis ◽  
Catalytic Effects ◽  
Hydrolysis Of

The catalytic effects of lanthanum ion on the rate of hydrolysis of p-nitrophenyl hydrogen methylphosphonate in aqueous solution at pH > 7.0 are reported. Increases in rate by a factor of about 3.6 × 104 have been observed. No such catalysis was found for diesters of methylphosphonic acid.

scholarly journals In Vitro and In Vivo Activities of Syn2190, a Novel β-Lactamase Inhibitor

1999 ◽  
Vol 43 (8) ◽  
pp. 1895-1900 ◽  
Author(s):  
Kouichi Nishida ◽  
Chieko Kunugita ◽  
Tatsuya Uji ◽  
Fusahiro Higashitani ◽  
Akio Hyodo ◽  
...  
Keyword(s):  
Systemic Infection ◽  
Side Chain ◽  
Infection Model ◽  
Morganella Morganii ◽  
Infection Models ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Group 1

ABSTRACT Syn2190, a monobactam derivative containing 1,5-dihydroxy-4-pyridone as the C-3 side chain, is a potent inhibitor of group 1 β-lactamase. The concentrations of inhibitor needed to reduce the initial rate of hydrolysis of substrate by 50% for Syn2190 against these enzymes were in the range of 0.002 to 0.01 μM. These values were 220- to 850-fold lower than those of tazobactam. Syn2190 showed in vitro synergy with ceftazidime and cefpirome. This synergy was dependent on the concentration of the inhibitor against group 1 β-lactamase-producing strains, such as Pseudomonas aeruginosa, Enterobacter cloacae, Citrobacter freundii, and Morganella morganii. However, against β-lactamase-derepressed mutants of P. aeruginosa, the MICs of ceftazidime plus Syn2190 were not affected by the amount of β-lactamase, and the values were the same for the parent strains. The MICs at which 50% of isolates are inhibited (MIC50s) of ceftazidime plus Syn2190 were 2- to 16-fold lower than those of ceftazidime alone for ceftazidime-resistant, clinically isolated gram-negative bacteria. Similarly, the MIC50s of cefpirome plus Syn2190 were two- to eightfold lower for cefpirome-resistant clinical isolates. The synergies of Syn2190 plus ceftazidime or cefpirome observed in vitro were also reflected in vivo. Syn2190 improved the efficacies of both cephalosporins in both a murine systemic infection model with cephalosporin-resistant rods and urinary tract infection models with cephalosporin-resistant P. aeruginosa.

THE HYDROLYSIS OF ACETIC ANHYDRIDE IN WATER AND IN THE SYSTEM WATER: METHYL ETHYL KETONE

1950 ◽  
Vol 28b (11) ◽  
pp. 663-670
Author(s):  
E. N. Banks ◽  
A. E. Marshall ◽  
R. W. Vollett ◽  
R. R. McLaughlin
Keyword(s):  
Acetic Anhydride ◽  
Methyl Ethyl Ketone ◽  
Catalytic Effect ◽  
Methyl Ethyl ◽  
Initial Concentration ◽  
Velocity Constant ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Order Rate Equation ◽  
System Water

The rate of hydrolysis of acetic anhydride at 25 °C. in water (I), in solutions of methyl ethyl ketone (MEK) in water (II), and in solutions of water in MEK (III) have been studied. In I the observation of previous investigators that the velocity constant varies linearly with the initial concentration of acetic anhydride, but for any given initial concentration of acetic anhydride the reaction is pseudomonomolecular, was confirmed and extended. In II the velocity constant is lower than in I and decreases linearly with increasing concentration of MEK, but, again, the reaction is pseudomonomolecular for any given initial concentration of acetic anhydride. An equation and a nomogram that relate the velocity constant to the initial concentration of acetic anhydride, MEK, and water are presented. In III the second-order rate equation must be modified to compensate for the presumed catalytic effect of the hydrogen ion produced by hydrolysis.

REACTIONS OF SULPHONIC ESTERS: VI. THE TEMPERATURE DEPENDENCE OF THE RATE FOR THE HYDROLYSIS OF A SERIES OF ALKYL BENZENESULPHONATES

1957 ◽  
Vol 35 (7) ◽  
pp. 613-622 ◽  
Author(s):  
R. E. Robertson
Keyword(s):  
Transition State ◽  
Temperature Dependence ◽  
Methyl Ethyl ◽  
Temperature Dependent ◽  
Temperature Coefficients ◽  
Nucleophilic Displacement ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Data are presented showing temperature dependence of the rate of hydrolysis of methyl, ethyl, isopropyl, and n-propyl benzenesulphonates in water. The heat of activation is shown to be temperature dependent to the extent of −30 to −40 cal./mole deg. Since, in solvolysis, the properties of water favor ionization over nucleophilic displacement, it is suggested that these temperature coefficients, ΔCp‡, and the accompanying entropy differences, ΔS‡, can be rationalized in terms of variations in the reorganization of the solvent about the transition state.

Effect of the basic amino-acid side chain length and the penultimate residue on the hydrolysis of benzoyldipeptides by carboxypeptidase B

1978 ◽  
Vol 56 (5) ◽  
pp. 315-318 ◽  
Author(s):  
Graham J. Moore ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acid ◽  
Chain Length ◽  
Basic Amino Acid ◽  
Side Chain ◽  
Amino Acid Side Chain ◽  
Carboxypeptidase B ◽  
Side Chain Length ◽  
C Terminus ◽  
Guanidino Group ◽  
Hydrolysis Of

The kinetic parameters Km and kcat/Km have been determined for the carboxypeptidase B (CPB, EC 3.4.12.3) catalyzed hydrolysis of benzoylglycyl-DL-homolysine and benzoylglycyl-L-homoarginine. Plots of these data and those for Bz-Gly-Orn and Bz-Gly-Arg (Wolff, E. C., Schirmer, E. W. &Folk, J. E. (1962) J. Biol. Chem. 237, 3094–3099) and Bz-Gly-Lys versus the length of the side chain of the basic amino acid indicate that unlike trypsin (EC 3.4.21.4) (Seely, J. H. &Benoiton, N. L. (1970) Can. J. Biochem. 48, 1122–1131) CPB has a higher binding affinity for a guanidino group than for an amino group at the side chain of the substrate C-terminus. On the other hand, CPB is similar to trypsin (ibid) in that the best substrate would have a side chain length between those of lysine and arginine.Studies with Bz-MeGly-Lys and Bz-Ala-Lys showed that the former is very slowly hydrolyzed by CPB but that the latter is a good substrate, with a high affinity for the enzyme, indicative of considerable participation of the Cα-methyl group of alanine in the binding of the substrate to the enzyme.

Kinetics of pyroarsenate hydrolysis in aqueous solution

1977 ◽  
Vol 30 (6) ◽  
pp. 1187 ◽  
Author(s):  
TG Richmond ◽  
JR Johnson ◽  
JO Edwards ◽  
PH Rieger
Keyword(s):  
Aqueous Solution ◽  
Rate Constant ◽  
Activation Parameters ◽  
Hydrolysis Rate ◽  
Associative Mechanism ◽  
Hydrolysis Rate Constant ◽  
Rate Of Hydrolysis ◽  
Ph Stat ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of pyroarsenate in 0.1 mol dm-3 NaClO4 solutions, pH 6-9, was measured by a pH-stat technique at temperatures ranging from 278 to 298 K. The pKa of HAs2O73-, found to be the predominant reactant under these conditions, was 7.3 and 7.6 at 283 and 298 K, respectively. The hydrolysis rate constant for HAs2O73- was 0.05 s-1 at 298 K with activation parameters ΔH? = 49 � 9 kJ mol-1 and ΔS? = -107 � 30 J mol-1 K-1. An associative mechanism is indicated.

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.

Oxidation of Acetone and Methyl Ethyl Ketone by Ceric Ions in Aqueous Solution

1958 ◽  
Vol 16 (1_2) ◽  
pp. 73-84 ◽  
Author(s):  
S. Venkatakrishnan ◽  
M. Santappa
Keyword(s):  
Aqueous Solution ◽  
Methyl Ethyl Ketone ◽  
Methyl Ethyl

METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

1961 ◽  
Vol 36 (4) ◽  
pp. 511-519 ◽  
Author(s):  
Margaret Wiener ◽  
Charles I. Lupa ◽  
E. Jürgen Plotz
Keyword(s):  
Rat Liver ◽  
Human Placenta ◽  
Steric Hindrance ◽  
Placental Tissue ◽  
Caproic Acid ◽  
Major Product ◽  
Side Chain ◽  
Anaerobic Conditions ◽  
Prolonged Action ◽  
Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

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