Introduction to enzymes
In a quantitative way, we have many more structural proteins in living creatures (proteins that form tissue like skin and hair, meat, etc.
However, the other type of proteins, not in enormous amounts, is at least if not more important: the catalysts of the biochemical processes, the enzymes.
A touch of history
Louis Pasteur (1822 -1895) was one of the scientists investigating that being catalised by enzymes. He believed that living bacteria were needed vor such reactions and called the proces fermentation, like the transformation of glucose in alcohol.
In 1897 Eduard Büchner made a filtrate without cells, containing the separated enzymes. For that, he treated the yeast cells with fine sand.
The enzymes in the filtrate ware very well capable to trasfer glucose into alcolhol.
Thats how he proved that for enzyme acivity the presence of living cells is not needed.
Büchner received therefor the Nobel price for chemistry in 1907.