A method for the rapid modification under mild conditions of carboxyl groups in proteins has been developed. The method involves the activation of the carboxyl group by a water-soluble carbodiimide and the subsequent reaction of the activated carboxyl group with a nucleophile such as glycine methyl ester. The kinetics of the reaction indicates that there are limits to the variation of carbodiim...

Carboxyl groups i n porcine pepsin were chemically modified "by the carbodiimide reaction using waterrsoluble l-ethyl-3-(3-dimethylaminopropyl) carbodiimide and amino acid esters as nucleophiles. The modification resulted in profound changes in the a c t i v i t i e s , specificity and.some physicochemical properties of the enzyme. These include* (1) significant decrease in milk clotting activi...

We have used pHLIP® [pH (low) insertion peptide] to study the roles of carboxyl groups in transmembrane (TM) peptide insertion. pHLIP binds to the surface of a lipid bilayer as a disordered peptide at neutral pH; when the pH is lowered, it inserts across the membrane to form a TM helix. Peptide insertion is reversed when the pH is raised above the characteristic pK(a) (6.0). A key event that fa...

A method has been developed to demonstrate the alpha-acylamido carboxyl groups of protein, taking advantage of the fact that acylamido carboxyl groups are converted to ketonic carbonyls by the action of acetic anhydride and absolute pyridine. The method utilizes deparaffinized sections of tissues fixed in a variety of fixatives. Following the conversion of carboxyls to the methyl ketones, the l...

Complexometric titration was used to determine the carboxyl group content of a series of oxidatively treated (selective and non-selective oxidation) nature cellulose fibers (cotton). The results were correlated with those obtained from the conventional methylene blue method; both methods show an excellent correlation. The progress of the cellulose fibers oxidation was monitored using viscosimet...

It has been found that ultrasonic treatment of diamond nanopowders contributes to surface cleaning due the removal non-diamond carbon and impurities from boundary nanodiamond grains (from 0.4 0.32 % for ASUD-99 0.67 0.55 ASUD 75, respectively). does not affect total sorption volume values specific studied samples do change, but it changes composition groups on nanoparticles, which its hydrophil...

In the structure of the title compound, NH(4) (+)·C(8)H(11)O(4) (-), the carboxyl and carboxyl-ate groups of the cation adopt C-C-C-O torsion angles of 174.9 (2) and -145.4 (2)°, respectively, with the alicyclic ring. The ammonium H atoms of the cations give a total of five hydrogen-bonding associations with carboxyl-ate O-atom acceptors of the anion which, together with a carboxyl O-H⋯O(carbox...