Caffeine and Molecular Interactions

Caffeine and Adenosine Receptors

Introduction

• Caffeine is a common substance with well-known effects, such as promoting alertness and boosting energy.

• It's found in coffee, energy drinks, and some medications and is often associated with sports for its energy-boosting properties.

Caffeine's Mechanism of Action: Blocking Adenosine Receptors

• Caffeine works by blocking adenosine receptors in the brain.

• Adenosine is a chemical that promotes relaxation and sleepiness by binding to its receptors.

Molecular Mimicry: How Caffeine Binds

• Caffeine's structure mimics that of adenosine, allowing it to bind to the same receptors.

• However, caffeine's structure differs enough that it doesn't activate the receptor in the same way adenosine does.

Activation vs. Blocking

• Activation of adenosine receptors makes you feel tired.

• Caffeine blocks these receptors but doesn't fully activate them, preventing the feeling of tiredness.

The Role of Methyl Groups

• The presence of methyl groups (CH3) on the caffeine molecule affects its ability to activate adenosine receptors.

• Caffeine binds to the receptors, occupying the space but not perfectly fitting to trigger the same response as adenosine.

Visualizing the Interaction

• Imagine a receptor with three arms; adenosine fits perfectly, activating it.

• Caffeine occupies the space, blocking adenosine, but doesn't fill all the arms, thus not activating the receptor.

Structural Comparison: Adenosine vs. Caffeine

• Adenosine has a larger structure than caffeine, including a ribose sugar group.

• Caffeine only occupies part of the receptor site, while adenosine needs to occupy the entire receptor to activate it.

Intermolecular Forces: Pi-Pi Stacking

• Pi-Pi stacking allows the caffeine to bind with the adenosine receptor in our brain; this causes us to feel less tired but this configuration does not activate the tired part of the receptor.

• This is a binding system between the receptor and the caffeine.

• Pi-Pi stacking is based on hydrogen interactions and the shape of the molecule.

Intermolecular Forces and Asymmetry

• Asymmetrical shapes of molecules causes interaction of intermolecular forces.

• Symmetrical molecules have very low polarity, making binding harder due to the lack of areas with high electron density or positive and negative charges.

Resonance and London Dispersion Forces

• Resonance in molecules, like benzene, contributes to stability due to overlapping p orbitals.

• Pi stacking modifies or reduces the dominance of London dispersion forces, with stronger interactions stabilizing the structure.

• Electron delocalization in aromatic systems reduces fluctuations in electron density.

London Dispersion Forces and Electron Stability

• London dispersion forces rely on temporary imbalances in electron distribution.

• Electron delocalization stabilizes electron distribution which reduces such imbalances.

Pi Stacking and Molecular Orientation

• Pi stacking tends to hold molecules in specific, less flexible orientations.

• London dispersion forces, conversely, are more random.

• Pi stacking overpowers or lessens the effect of London dispersion forces.

Interactive Activity

• Consider starting with a quick poll: How many people drink coffee? How many cups? How many milligrams of caffeine do they think they consume?

Additional Research

• Caffeine has been researched to show that it may decrease the risk of Parkinson's disease.

Concluding Remarks

• Clarify the structural differences between adenosine and caffeine visually.

• Emphasize how they complement each other in binding but differ in receptor activation.

• Time the presentation to ensure that the time does not exceed allocated timeframe, accounting reading speed.