A new computational method for analyzing the protonation states of protein-ligand complexes with multiple ionizable groups is applied to the structurally characterized complex between the peptide Glu-Asp-Leu and HIV-1 protease. This complex has eight ionizable groups at the active site: four from the ligand and four Asp residues on the protein. Correlation, with an error of ca. 0.6 kcal mol-1, ...

Introduction Trhe titration curve for the expressed juice of etiolated wheat seedlings has a pronounced inflection above pH 8.0 (fig. 4), which does not occur in the curve for fully green seedlings (fig. 5). An intermediate type of curve, linear between p1I 8.5 and 11.0, is characteristic of very young seedlings just after their emergence from the ground. when, from the standpoint of chemical c...

The formol titration, as described by Srrensen, 1 has been most useful in the determination of amino-acids and especially in following the course of hydrolysis of proteins. The method as originally described could not be used for accurate determinations of small quantifies of amino-acids owing to the difficulty of determining the exact end-point. The value obtained also depends on the point at ...

The influence of temperature on the titration curve of casein may be accounted for by the Bjerrum theory of ionization of ampholytes.

Batch potentiometric titration analyses were made on a 7-Al,O, colloidal suspension and interpreted in terms of the electroneutrality principle. Three titration methods involving a singular reference curve were compared. The first reference used was theoretical, the latter two were representative supernatant curves: an electrolyte solution, and an aliquot of the zero point of titration (ZPT) su...

Determining the surface protonation behavior of natural adsorbents is essential to understand how they interact with their environments. ProtoFit is a tool for analysis of acid–base titration data and optimization of surface protonation models. The program offers a number of useful features including: (1) enables visualization of adsorbent buffering behavior; (2) uses an optimization approach i...

Isothermal titration calorimetry (ITC) is one of the most interesting methods for the characterization of the interaction mechanisms of cyclodextrins (CDs) with drugs. In this review we explain how to conduct ITC experiments correctly for CD-guest interactions, how to choose an accurate fitting model for the titration curve and how to interpret carefully the ITC results. Finally, the use of ITC...

A PDP-II online computer method for the titration of mixtures or 3 strong and a weak acid is described. The method is based on multiparametric curve-fitting. One of the parameters found from the calculations is the dissociation constant of the weak acid, hence the method can be applied even when this constant is unknown. Accurate results (relative error * 1%) were obtained for weak acids with p...

The interaction of the dye reactive bright red 6C with bovine serum albumin has been investigated. Formation of a complex between reactive bright red 6C and bovine serum albumin was detected by use of absorption difference spectroscopy. The curves obtained by titration of the protein against the dye were recorded at different pH and ionic strength of the solution. An unusual form of titration c...