Diastase

Payen and Persoz isolate and name diastase from germinated barley

A little of the white powder reportedly altered some 2,000 times its own weight of starch within minutes — and boiling destroyed the power completely.

Sprouted barley, cold water, alcohol

In 1833 Anselme Payen and Jean-François Persoz crushed germinating barley in cold water and used alcohol to precipitate a white, nitrogen-containing preparation out of the extract.

The preparation rapidly liquefied starch and converted it into dextrin and sugar; a dilution of 1:1,000 was reported to degrade starch quickly.

Boiling destroyed its activity — an early experimental glimpse of how heat-sensitive these agents are.

Why "diastase"

They named it for its separating action on the contents of starch granules, not — as is often repeated — because it separated a seed's husk during heated beer mashing.

Their memoir, "Mémoire sur la diastase, les principaux produits de ses réactions et leurs applications aux arts industriels," occupies pages 73–92 of volume 53 of the Annales de chimie et de physique.

The word ending now familiar from lactase and polymerase traces back through that name.

First isolated, not first observed

Calling diastase the first enzyme is retrospective. Dubrunfaut had already described the starch-converting action of malt extract in 1830.

What Payen and Persoz did was separate the active principle from the organised plant material, so that it could be concentrated, dried, preserved and studied on its own.

The term "enzyme" was introduced only later, by Wilhelm Kühne in 1876, and their diastase was a crude mixture of malt amylase activities rather than a single purified protein.

Sources

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What the sources leave uncertain

No exact day for the laboratory isolation has been established; 1833 is the secure publication and reporting year.
A report on the work was associated with the Académie des sciences on 17 June 1833, but that is a review date, not necessarily the date of discovery.
Calling it the “first enzyme” is retrospective. Dubrunfaut had described the starch-converting action of malt extract in 1830; Payen and Persoz's distinction was isolating and preserving the active preparation.