3D Enzyme–Substrate Interactions Simulation
Lock-and-key specificity, induced fit and catalysis

Enzyme kinetics laboratory

Mission: choose a substrate shape and an active-site shape. Only matching shapes can enter the pocket and complete catalysis.
60 µM
25 °C
7.0
90%
0%
1×

Live measurements

Catalytic stageDiffusing
Reaction rate0%
Active enzyme0%
Products formed0

The enzyme and substrate are ready. Press Start to observe one complete catalytic cycle.

Enzyme kinetics graph

Reaction rateProduct accumulation

Microscope & camera

Focus: noneTap a molecule
1.0×

Drag to pan. Wheel or pinch to zoom. Tap the enzyme, active site, substrate, catalytic residues, transition state, products, inhibitor, allosteric site, cofactor, or water for a compact molecular view.

Teacher / Demo tools

Interactive teacher-led lesson

The lesson begins immediately. Each sentence changes the active shape, arrow, camera, and microscopic process before continuing.

Ready. Narration will not start automatically.
Step 0 of 120%

Ready for the enzyme–substrate lesson

What to watch: press Start Complete Lecture.

The lesson begins only when you choose to start it.

Learning objectives

  • Trace every stage of an enzyme catalytic cycle.
  • Use circle, triangle, square, and hexagon pairs to explain lock-and-key specificity.
  • Distinguish the classic lock-and-key model from induced fit.
  • Relate transition-state stabilization to lower activation energy.
  • Predict how substrate concentration, temperature, pH, and inhibitors change reaction rate.
  • Distinguish competitive inhibition from allosteric regulation.

Key concepts demonstrated

The lock-and-key model says a substrate must have a complementary shape to enter an enzyme active site: circle matches circle, triangle matches triangle, square matches square, and hexagon matches hexagon. Real enzymes then improve this initial match through induced fit. Catalysis stabilizes a transition state, and the enzyme is regenerated after product release.

Suggested experiments

  • Raise substrate concentration until reaction rate approaches a plateau.
  • Compare 10 °C, 37 °C, and 60 °C.
  • Move pH away from 7 and watch catalytic residues lose their useful charge pattern.
  • Add competitive inhibitor, then raise substrate concentration to observe competition.

Questions for exploration

  • Why does reaction rate saturate even when more substrate is added?
  • How does induced fit improve catalysis?
  • Why can extreme pH reduce activity without breaking peptide bonds immediately?

Real-world applications

Enzyme kinetics guides drug design, clinical diagnostics, digestion, fermentation, biotechnology, metabolic engineering, and treatment of enzyme deficiencies.

Common misconceptions

  • Enzymes do not supply energy or change reaction equilibrium.
  • An enzyme is not consumed during a normal catalytic cycle.
  • The active site is flexible, not a rigid hole.
  • More substrate cannot increase rate beyond enzyme saturation.

Enzyme–substrate challenge

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