Acid dissociation constant and apparent nucleophilicity of lysine-501 of the .alpha.-polypeptide of sodium and potassium ion-activated adenosinetriphosphatase

Biochemistry ◽  
1989 ◽  
Vol 28 (17) ◽  
pp. 6894-6899 ◽  
Author(s):  
Kai Yuan Xu
Keyword(s):  
Dissociation Constant ◽  
Potassium Ion ◽  
Acid Dissociation ◽  
Acid Dissociation Constant ◽  
Sodium And Potassium

Accurate acid dissociation constant (pKa) calculation for the sulfachloropyridazine and similar molecules

2021 ◽  
Vol 27 (8) ◽  
Author(s):  
Fernando Marques Carvalho ◽  
Yuri Alves de Oliveira Só ◽  
Alessandra Sofia Kiametis Wernik ◽  
Mônica de Abreu Silva ◽  
Ricardo Gargano
Keyword(s):  
Dissociation Constant ◽  
Acid Dissociation ◽  
Acid Dissociation Constant ◽  
Pka Calculation

scholarly journals pKa and Ka (Acid dissociation constant)

2020 ◽  
pp. S108-S108
Author(s):  
G Manjooran
Keyword(s):  
Dissociation Constant ◽  
Acid Dissociation ◽  
Acid Dissociation Constant

pKa of a drug is the pH at which 50% of the drug is ionised and 50% is not ionised/unionised. The pKa is specific for each drug and these properties determine how a drug can be administered, the speed of absorption as well as speed of excretion by the kidneys.

Chromatographic Determination of Thermodynamic Acid Dissociation Constants of Tetracycline Antibiotics and Their Epimers

2019 ◽  
Vol 57 (8) ◽  
pp. 745-750
Author(s):  
İlkay Konçe ◽  
Ebru Çubuk Demiralay ◽  
Hülya Yılmaz Ortak
Keyword(s):  
Experimental Data ◽  
Dissociation Constant ◽  
Binary Mixtures ◽  
Dissociation Constants ◽  
Reversed Phase ◽  
Acid Dissociation ◽  
Acid Dissociation Constant ◽  
Chromatography Method ◽  
Ph Values

Abstract The presented study describes the development of reversed-phase liquid chromatography method using a core-shell particle column with a pentafluorophenyl stationary phase for the dissociation constant (pKa) determination of the tetracycline group antibiotics (tetracycline, oxytetracycline, chlortetracycline) and their epimers (4-epitetracycline, 4-epioxytetracycline, 4-epichlortetracycline). The pH values were measured in the acetonitrile (ACN)–water binary mixtures, used as mobile phases, instead of in water and take into account the effect of the activity coefficients. Thermodynamic acid dissociation constant (pKa1) values of studied antibiotics and their epimers were calculated using retention factor (k) at different mobile phase pH values in studied binary mixtures with ACN percentages of 20, 25, 30 and 35% (v/v). Experimental data were analyzed by using an Origin 7.0 program to fit experimental data to the nonlinear expression derived. From calculated pKa1 values, the aqueous pKa values of studied compounds were calculated by different approaches and these values were compared.

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