Receptor-ligand dissociation constant?


Question by: Caio Marino | Last updated: January 8, 2022

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Ka = [RX]/[X][R]

The dissociation constant (Kd) is the inverse of the association constant. Kd is also used to know the affinity of a drug for its receptor.

How to calculate acid dissociation constant?

This value is given by the difference between the initial Ca concentration of the undissociated acid (0.315 mol / L) and the concentration of the acid which dissociates and which therefore forms the H + ion and the NO2- ion (0.0117 mol / L). L). Therefore the Ka value of nitrous acid at the given temperature is 4.51 · 10-4.

How is the dissociation constant calculated?

Calculation of Ka or Kb from the degree of dissociation

  1. α = nd/ noor
  2. 1) A weak acid HA has a concentration of 0.200 M and its degree of dissociation is 1.235%. …
  3. 2) Methylamine CH3NH2 it is a weak base; a 1.3 M solution of this base has a degree of dissociation of 0.72%.

What determines the binding of a ligand to its receptor?

The agonist binds to the receptor and causes a receptor modification. This modification can activate enzymes or open nearby ion channels. The RECEPTOR + AGONIST bond is reversible, therefore we speak of a very weak bond.

How is a receptor made?

In biochemistry, a receptor is a protein, transmembrane or intracellular, which binds with a specific factor, defined as a ligand, causing a conformational change in the receptor following which there is the onset of a cellular response or a biological effect.

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How many receptors are there?


What differentiates a receptor from a sense organ?

Sensory receptors are classified according to the origin of the stimulus: Teleceptors: sensitive to stimuli from afar. Esteroreceptors: sensitive to stimuli from external sources close to the body. Interceptors: sensitive to phenomena coming from within the organism.

What is the therapeutic effect of an antagonist drug due to?

The antagonists produce their effects by preventing the activation of receptors by the agonists. Antagonists can produce beneficial effects by blocking the actions of endogenous regulatory molecules or by blocking the action of drugs.

What are antagonistic interactions?

The term antagonism generically refers to an interaction that leads to a loss of effect of a substance. The functional or physiological antagonism concerns substances that act on different receptors that have contrasting effects (eg: histamine / noradrenaline).

What determines the binding of hormones to specific receptors?

The hormone-receptor link acts like a key in the lock: it opens the door (triggers an intracellular reaction) only if the key is the right one. By binding to the receptor, the hormone determines a structural variation and therefore a series of changes within the cell.

How is Ka calculated?

A weak acid HA is characterized by the following ionization equilibrium:

  1. HA ⇔ H+ + A
  2. Kto = [H+]×[A]/[HA]
  3. Kto = 103 × 103 / 0.1 = 105

What is the dissociation constant of water?

Dissociation of water

Water is a very weak electrolyte and in fact its K.diss at 25 ° C it is 1.8 • 1016. The H ion+which dissociates from the H molecule2O immediately binds to another molecule of H.2OR; therefore the dissociation equilibrium of water should be written between two molecules of H2OR.

How is dissociation done in chemistry?

In the representation of dissociation (or more precisely ionization), the formula of the acid residue is written by reporting the four oxygen atoms after the sulfur symbol indicating, on the top right, the two negative charges without specifying on which of the two atoms they are placed.

How do you define the acid or base constant of a substance?

The acid dissociation constant, (also called the acid ionization constant, or acid protolysis constant), represented by the symbol Ktois a value that measures, at a given temperature, the degree of dissociation of an acid in solution.

How to calculate Ka with KB?

Let’s take another example. There is therefore an equilibrium with a constant and it is called Kb because it refers to a base. We also remember that Kw = Ka x Kb for which Kb = Kw / Ka which means that if we know the Kb for a base, its Ka can be obtained from Kw / Kb.

How is the strength of an acid measured?

The strength of an acid depends on the strength of the HA bond and the stability of the conjugate base. The stronger an acid, the weaker its conjugate base. In aqueous solutions, the strength of acids measures the tendency to release protons to water, the strength of bases measures the tendency to acquire protons from water.

What is the antagonist drug?

We speak of pharmacokinetic or indirect antagonism when a substance interferes with the pharmacokinetics of the drug (absorption, metabolism and elimination).

What is meant by pharmacokinetics?

pharmacokinetics Study of the temporal evolution of drug concentration in the body. It is ideally divided into four phases: absorption, distribution, metabolism, excretion.

What do agonist drugs do?

Agonists are intrinsically active molecules capable of mimicking the effects of the ligand. When they bind to the receptor, they cause conformational changes of similar magnitude to those caused by binding to the endogenous ligand.

What is an agonist and antagonist drug?

Agonists and antagonists

Drug that binds to the receptor and activates it and that mimics the effect of the endogenous Ligand. The antagonist is a drug that binds to a receptor and is unable to activate it but inhibits, partially or totally, the effect of the agonist (or endogenous ligand) acting on the same receptor.

What does the potency of a drug express?

In pharmacology, the potency of a drug is an indicator of its activity, defined as the concentration required to provoke a response of a certain intensity.

How long does the effect of a drug last?

Some pharmaceutical products are specially formulated to release the active ingredients slowly or in small, repeated quantities over time, usually over a period of 12 hours or more.

Who has no sense of touch?

What are the sense organs for? The sense organs are those organs (eyes, ear, mouth, nose and skin) that allow man to interact at different levels with the world around him.

What is the function of the five senses?

The sense organs are those that allow humans to interact with the surrounding environment. Each of the sense organs corresponds to one of the five senses: eyes and sight. Ears and hearing, mouth and taste, nose and smell, skin and touch.

Which and how many sense organs are there?

Sensory organs

  • eyes – sight.
  • ears – hearing.
  • mouth – taste.
  • nose – smell.
  • skin – touch.


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