Historical figure · Pearson Edexcel International GCSE revision on Incandio

Emil Fischer

Who Said A Lock Must Fit Its Key · Chemist · 1852–1919

The chemist who built the sugars atom by atom, named the peptide bond, and proposed that an enzyme fits its substrate like a lock and its key.

Defend these ideas against Fischer

Incandio is a free revision platform for the Pearson Edexcel International GCSE, and on it a topic counts as mastered only once you have learned it, proved it in questions, taught it back and defended it against the person with the strongest claim on it. Emil Fischer is that person for 4 topics on the course:

• Enzymes: Catalysts With a Shape — Biology
• Carbohydrates, Proteins and Lipids — Biology
• How Mutations Affect Proteins — Biology
• Esters And How To Make One — Chemistry

Who was Fischer?

Emil Fischer was born at Euskirchen in 1852. His father, a merchant, tried to bring him into the family business, concluded he was too stupid for it, and sent him to university instead. He studied under Adolf von Baeyer and spent the next four decades on the two classes of molecule that living things are mostly built from. First the sugars: he determined the structures of glucose, fructose, mannose and their relatives, not by inspection but by building and degrading them and by reading how each solution rotated polarised light. In doing so he had to confront molecules that contain the same atoms joined in the same order and yet differ, as a left hand differs from a right. That produced the observation his name carries in biology. Testing yeast preparations against pairs of such mirror-image sugars, he found that one would be fermented completely and the other left entirely alone — identical chemistry, opposite arrangement in space. In 1894 he drew the conclusion: enzyme and substrate must fit one another, in his own phrase, like a lock and its key, and this is why an enzyme acts on one substance and refuses its near neighbours. He then turned to the proteins, established that they are chains of amino acids joined by a linkage he named the peptide bond, and synthesised such chains himself. He received the Nobel Prize in Chemistry in 1902. His health was permanently damaged by years of exposure to phenylhydrazine, and he lost two of his three sons in the First World War. He died in 1919.

Major achievements

• Determined the structures of glucose, fructose, mannose and the other sugars, and synthesised them
• Proposed the lock-and-key model of enzyme action in 1894
• Established that proteins are chains of amino acids and named the peptide bond
• Synthesised peptide chains of up to eighteen amino acids
• Worked out the structures of the purines, including caffeine and uric acid

Life in brief

• 1852 — Born at Euskirchen: Judged unfit for the family business and sent to university.
• 1875 — Discovers phenylhydrazine: The reagent that unlocked the sugars, and that wrecked his health.
• 1884 — The sugars: Begins the decade of work that determines their structures.
• 1894 — Lock and key: Concludes from mirror-image sugars that enzyme and substrate must fit in shape.
• 1902 — Nobel Prize: For the work on sugars and purines.
• 1907 — The peptide bond: Chains of amino acids built to eighteen units.
• 1919 — Dies in Berlin: After the war took two of his sons.

Explore the life of Fischer — five chapters

1. Too Stupid for the Family Business — Euskirchen, and a reagent that made a career
2. Sixteen Sugars, and Which Is Which — Working out glucose in the dark
3. The Yeast That Refused — 1894, and the evidence behind the lock and key
4. The Peptide Bond — Proteins as chains, and eighteen units built by hand
5. Two Sons, and the End — War work, loss, and a model that had to be softened

Read the five-chapter life of Emil Fischer →

Where Fischer appears in your course

Emil Fischer has a genuine claim on 2 lessons of the Pearson Edexcel International GCSE science course built into Incandio:

• Enzymes: Catalysts With a Shape — Biology: The lock-and-key picture on this page is Fischer's, proposed in 1894. Working with two sugars built from exactly the same atoms, he found that an enzyme would act on one and completely ignore the other — so the difference between them could only be one of shape, and he concluded that enzyme and substrate must fit each other like a lock and its key. Every explanation on this page rests on that one idea.
• Enzymes and pH — Biology: This lesson explains that pH ruins an enzyme by changing the shape of its active site. That only means anything because of Fischer's 1894 proposal that enzyme and substrate fit together like a lock and its key — the idea that makes a change of shape a catastrophe rather than a detail.

Begin

• Start a conversation with Fischer — a dramatised, historically grounded AI portrayal
• Read the Historical Brief
• Explore the life of Fischer — five chapters
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