CHEMISTRY OF THE TRIFLUOROMETHYL GROUP: PART IV. DIPHENYLTRIFLUOROMETHYLPHOSPHINE AND COMPLEX FORMATION BY PHENYLTRIFLUOROMETHYLPHOSPHINES

1962 ◽  
Vol 40 (2) ◽  
pp. 283-288 ◽  
Author(s):  
M. A. A. Beg ◽  
H. C. Clark
Keyword(s):  
Complex Formation ◽  
Trifluoromethyl Group ◽  
Hydrolysis Of ◽  
Group Part

Three methods of preparing diphenyltrifluoromethylphosphine are described. The hydrolysis of the phosphine to diphenylphosphinic acid and fluoroform, and the formation of dibromo-and diiodo-phosphoranes from the phosphine are reported. The adducts (C6H5)3P•BF3 and (C6H5)2CF3P•BF3 are described and the latter is found to be the less stable. With platinum (II) chloride, the complexes trans-[(C6H5)2PCF3]2PtCl2 and trans-[C6H5PCF3)2]2PtCl2 are formed. The properties of the BF3 adducts and PtCl2 complexes are interpreted in terms of the electronegativity and size of the trifluoromethyl group.

CHEMISTRY OF THE TRIFLUOROMETHYL GROUP: PART I. COMPLEX FORMATION BY PHOSPHINES CONTAINING THE TRIFLUOROMETHYL GROUP

1960 ◽  
Vol 38 (1) ◽  
pp. 119-124 ◽  
Author(s):  
M. A. A. Beg ◽  
H. C. Clark
Keyword(s):  
Complex Formation ◽  
Boron Trifluoride ◽  
Trifluoromethyl Group ◽  
Bonding Properties ◽  
New Compounds ◽  
Group Part

The formation of co-ordination compounds of (CH3)3P, (CH3)2PCF3, CH3P(CF3)2, and P(CF3)3, with boron trifluoride and platinum (II) chloride has been studied. The properties of the new compounds (CH3)2PCF3.BF3, [(CH3)2PCF3]2PtCl2, [CH3P(CF3)2]2PtCl2 are described, and it is hence concluded that the stabilities of the boron trifluoride compounds decrease in the order.[Formula: see text]while for the platinum (II) complexes the order of stability is[Formula: see text]These two orders are related to the electronegativity of the trifluoromethyl group and its influence on the bonding properties of the phosphorus atoms.

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

pH Effects in trypsin catalysis

1969 ◽  
Vol 47 (21) ◽  
pp. 4021-4029 ◽  
Author(s):  
H. P. Kasserra ◽  
K. J. Laidler
Keyword(s):  
Complex Formation ◽  
Ph Dependence ◽  
Specific Rotation ◽  
Ph Effects ◽  
Ph Values ◽  
A Value ◽  
Available Information ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Covalent Complex

A kinetic study has been made of the trypsin-catalyzed hydrolysis of N-benzoyl-L-alanine methyl ester, at pH values ranging from 6 to 10. The substrate concentrations varied from 1.7 × 10−3 to 4.3 × 10−2 M. From the rates were calculated, at each pH, values of [Formula: see text] (corresponding to [Formula: see text]), [Formula: see text] (corresponding to [Formula: see text]) and [Formula: see text] The specific levorotation of trypsin was measured and found to vary with pH in the pH region 5–11, the change in specific rotation following the ionization of a single group with pK(app) of 9.4. At pH 11 the specific rotation of trypsin, its zymogen, and its phosphorylated derivative were approximately the same, suggesting similar conformations for all three forms of the protein.The kinetic results on the acid side were very similar to those obtained by other investigators for chymotrypsin; they imply that there is a group of [Formula: see text] in the free enzyme, presumably the imidazole function of a histidine residue, and that this group is involved in acylation and deacylation, which can only occur if it is unprotonated. The behavior on the basic side was found to be different from that with chymotrypsin revealing a decrease in [Formula: see text] at high pH corresponding to a value of [Formula: see text] whereas [Formula: see text] showed sigmoid pH-dependence. An interpretation of these results that is consistent with all available information is that a group of [Formula: see text] (presumably the —NH3+ function of the terminal isoleucine) controls the conformation and thereby the activity of the enzyme at different stages of complex formation. In contrast to chymotrypsin, the pK of this ionizing group appears to be generally lowered by covalent complex formation between trypsin and its substrates.

scholarly journals Targeting PirAvp and PirBvp Toxins of Vibrio parahaemolyticus with Oilseed Peptides: An In Silico Approach

Antibiotics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1211
Author(s):  
Joe-Hui Ong ◽  
Wey-Lim Wong ◽  
Fai-Chu Wong ◽  
Tsun-Thai Chai
Keyword(s):  
Complex Formation ◽  
In Silico ◽  
Vibrio Parahaemolyticus ◽  
Water Solubility ◽  
Toxin Binding ◽  
Binding Peptides ◽  
Acute Hepatopancreatic Necrosis Disease ◽  
Hydrolysis Of ◽  
Tryptic Hydrolysis ◽  
Dual Target

Acute hepatopancreatic necrosis disease (AHPND), caused by PirAvp- and PirBvp-releasing Vibrio parahaemolyticus strains, has resulted in massive mortality in shrimp aquaculture. Excessive use of antibiotics for AHPND management has led to antibiotic resistance, highlighting the urgency to search for alternatives. Using an in silico approach, we aimed to discover PirAvp/PirBvp-binding peptides from oilseed meals as alternatives to antibiotics. To search for peptides that remain intact in the shrimp digestive tract, and therefore would be available for toxin binding, we focused on peptides released from tryptic hydrolysis of 37 major proteins from seeds of hemp, pumpkin, rape, sesame, and sunflower. This yielded 809 peptides. Further screening led to 24 peptides predicted as being non-toxic to shrimp, fish, and humans, with thermal stability and low water solubility. Molecular docking on the 24 peptides revealed six dual-target peptides capable of binding to key regions responsible for complex formation on both PirAvp and PirBvp. The peptides (ISYVVQGMGISGR, LTFVVHGHALMGK, QSLGVPPQLGNACNLDNLDVLQPTETIK, ISTINSQTLPILSQLR, PQFLVGASSILR, and VQVVNHMGQK) are 1139–2977 Da in mass and 10–28 residues in length. Such peptides are potential candidates for the future development of peptide-based anti-AHPND agents which potentially mitigate V. parahaemolyticus pathogenesis by intercepting PirAvp/PirBvp complex formation.

Interaction of Thrombin with Antithrombin III and α2Macrogeobulin

1979 ◽  
Author(s):  
A. Takada ◽  
Y. Takada
Keyword(s):  
Complex Formation ◽  
Antithrombin Iii ◽  
Thrombin Activity ◽  
Presence And Absence ◽  
Hydrolysis Of

When one unit of thrombin was added to recalcified diluted plasma, more thrombin activity was shown in the presence of heparin than in its absence, but no difference was shown after two hour incubation. When one unit of thrombin was added to diluted plasma without the addition of Ca++, no difference in thrombin activities was shown in the presence and absence of heparin. When highly purified α2macroglobulin (α2M) and antithrombin III (ATIII) were used, thrombin activity was initially enhanced in the presence of either ATIII or ATIII, and quick inactivation of thrombin by ATIII regardless of the presence of heparin was observed. Electrophoresis shows that migrating patterns of ATIII depended upon amounts of heparin added to plasma, and ATIII migrated more to the anode with larger amounts of heparin. Thrombin-ATIII complex formed quickly in the undiluted recalcified plasma in the presence of heparin, but little complex formation was shown in the absence of heparin. When α2M was mixed with thrombin, and the mixture was added to TLMe at intervals, hydrolysis of TLMe was enhanced initially, then decreased quickly. α2M-thrombin complex seemed to be not as effective as free thrombin in the capacity to hydrolyze TLMe in contrast to α2M-trypsin or α2M-plasmin complex. α2M may be a primary inhibitor of thrombin in the plasma in the absence of heparin. In the presence of heparin, ATIII seems to be a primary inhibitor of thrombin.

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