RGI 8

Introduction

• A scenario depicting a man buying an antibiotic from a pharmacy.

• Pharmacist explains the action of beta-lactams and fluoroquinolones on bacteria.

Antibiotics and Their Mechanisms

• Beta-lactams:

  • Target cell wall synthesis.

  • Form peptide linkages during the cross-linking of peptidoglycan strands, involving carbonyl (C=O) functional groups.

• Fluoroquinolones:

  • Another class of antibiotics that target bacterial DNA replication.

Key Functional Groups and Enzymatic Reactions

• Enzymes: Essential for biochemical reactions in bacteria.

• **Active Site Components: **

  • Composed of serine amino acids, which have a functional group (–OH) that reacts with peptidoglycan strands.

• Enzymatic Process:

  • Enzyme binds to the first peptidoglycan strand.

  • A peptide bond is formed with the release of the enzyme.

Structural Components

• Insulin Structure:

  • Mention of its importance and comparison with beta-lactam antibiotics.

• Beta-lactam Structure:

  • Example Structure: Penicillin.

  • Formation of cyclic structure from combining cysteine and valence molecules leads to galactan.

Reactivity of Beta-lactams

• Ring Strain:

  • Beta-lactam antibiotics exhibit higher reactivity due to ring strain present in their four-membered ring compared to five or six-membered rings.

  • The strain is often described as a reactive half-open book.

Protein Hydrolysis and Enzyme Interaction

• Hydrolysis of Proteins:

  • Discussions around the ability to hydrolyze proteins and beta-lactams.

• Role of Enzymes:

  • Enzymes like GTPase interact with antibiotics, blocking their activity by removing critical components, undermining bacterial function.

• Lycopeptide Transpeptidase:

  • Explains how this enzyme reacts with beta-lactam antibiotics, forming ester bonds that make them nonreactive.

  • This binding keeps the enzyme in an active and happy state, allowing continued bacterial growth despite antibiotic presence.

Conclusion

• The overall mechanism of action, reactivity, and enzyme interaction forms the basis for understanding how antibiotics work and how bacteria can develop resistance.