Speed read: Preparing pure proteins
In the first half of the 20th century, crystallization of small simple molecules had become a vital process in understanding their chemical nature, but could crystallization also help in understanding the chemical nature of vital processes? Three scientists overcame the barrier of crystallizing proteins in different ways, and for their achievements they shared the Nobel Prize in Chemistry in 1946.
In 1926, James Sumner successfully crystallized an enzyme, called urease, for the first time, and with it he solved a contentious debate amongst biologists. For years researchers had studied the effects of enzymes – nature’s catalytic converters – without knowing anything definite about what they are, partly because they could not be isolated in the pure form. Despite several colleagues telling him that isolating an enzyme was a foolish task, Sumner proved urease could be crystallized, and that it could still carry out its catalytic reaction in the crystal state. Tests showed that urease is also a protein, making this the first ever protein to be crystallized.
Sumner’s findings were initially dismissed. However, building on this pioneering work, John Northrop developed the crystallization of pure enzymes and other proteins into an art form; and with it helped convince researchers that enzymes can be purified and isolated in tangible quantities. Northrop and his colleagues created the optimal conditions for successfully crystallizing a number of digestive enzymes, such as pepsin and trypsin. Through this, Northrop discovered interesting relationships between enzymes and related proteins, and this paved the way to developing a better understanding of how enzymes work.
The chemical make-up of viruses was as obscure as that of enzymes, before Wendell Stanley showed that the tobacco mosaic disease virus can be crystallized in the same way as proteins and enzymes. Stanley’s findings helped to open up an almost unlimited field of research – scientists could now crystallize a host of viruses, allowing them to investigate their precise structures and how to target them with treatments.
James B. Sumner – Nobel Lecture
Nobel Lecture, December 12, 1946
The Chemical Nature of Enzymes
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Pdf 163 kB
John H. Northrop – Nobel Lecture
Nobel Lecture, December 12, 1946
The Preparation of Pure Enzymes and Virus Proteins
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Pdf 335 kB
Wendell M. Stanley – Nobel Lecture
Nobel Lecture, December 12, 1946
The Isolation and Properties of Crystalline Tobacco Mosaic Virus
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Pdf 416 kB
Wendell M. Stanley – Other resources
Links to other sited
On Wendell Meredith Stanley from the American Association of Immunologists
On Wendell M. Stanley from Rockefeller University
James B. Sumner – Banquet speech
James B. Sumner’s speech at the Nobel Banquet in Stockholm, December 10, 1946
Your Royal Highnesses, Your Excellencies, Ladies and Gentlemen:
I am a plain man, just out of the laboratory, leaving my test tubes behind me. It is impossible for me to express our gratitude and our appreciation for the great honor which has been bestowed upon us today; nor can we thank you sufficiently for the gracious hospitality which has been extended to us.
I am both proud and happy to be associated with Dr. Northrop and with Dr. Stanley in this year’s award of the Nobel Prize in Chemistry, since I have, for a long time, admired the work of these two men.
Having learned to know and to love your beautiful country through the good fortune of making two previous extended visits, I am delighted to be able to be here again, even for a short period of time.
We American scientists appreciate the unique characteristics of the Nobel Prize awards, which are restricted neither by international frontiers, time, race, nor sex. We appreciate the wisdom of Alfred Nobel in founding the institution which bears his name. We realize fully the stimulus which this foundation gives to scientific research all over the world.
I thank you.
Prior to the speech, Sigurd Curman, President of the Royal Academy of Sciences, made this comment: “This year’s three prize-winners in chemistry: Professor James B. Sumner, Dr. John H. Northrop and Dr. W.M. Stanley, have all been rewarded for their epoch-making investigations into two groups of substances which play an important, if invisible, part in the existence of living organisms and which, on account of their different actions, we might well call ‘the promoters of life’ and ‘the enemies of life’. These are substances whose influence was previously known – enzymes and viruses. It is only now, through the efforts of the Nobel prize-winners, that they have been isolated and purified so that they can be produced in crystalline form. A more profound study of these mysterious substances, which are situated, so to speak, on the threshold of life, between living and dead matter, has thus been possible, They have a tremendous influence on the human organism, the enzymes as conveyors and regulators of the vital processes of the entire human body, and the viruses as disseminators of a number of the diseases most dangerous to mankind, such as smallpox, yellow-fever, infantile paralysis, influenza and so on. It is probable that this new knowledge as to the nature of the viruses will lead to the discovery of effective methods of fighting these scourges of humanity.
When we now offer you our congratulations, Gentlemen, we consider that we have every reason to call you, all three, ‘promoters of life’.”