mature Nobel in Chemistry pics Prize pics incest Nobel in ТМ Chemistry Трансформатор Prize под и саб опоры Prize разное Nobel Chemistry по короба стойки салону д in т проставки ass="smalltext">Presentation Speech* by Professor Karl Myrbäck, member of the Nobel Committee for Chemistry of the Royal Swedish Academy of Sciences
Your Majesty, Your Royal Highnesses, Ladies and Gentlemen.
The 1970 Nobel Prize for chemistry has been awarded to Dr. Luis Leloir for work
of fundamental importance for biochemistry. Dr. Leloir receives the prize for
his discovery of the sugar nucleotides and their function in the biosynthesis
of carbohydrates.
Carbohydrates, as everybody
knows, form a comprehensive group of naturally occurring
substances, which include innumerable sugars and sugar derivatives, as well
as high-molecular carbohydrates (polysaccharides) like starch and cellulose
in plants and glycogen in animals. A polysaccharide molecule is composed of
a large number of sugar or sugar-like units.
Carbohydrates are of great importance in biology. The unique reaction, which
makes life possible on Earth, namely the assimilation of the green plants, produces
sugar, from which originate, not only all carbohydrates but, indirectly, also
all other components of living organisms.
The important role of carbohydrates, especially sugars and starch, in human
food and, generally, in the metabolism of living organisms, is well known. The
biological break-down of carbohydrates (often spoken of as "combustion") supplies
the principal part of the energy that every organism needs for various vital
processes. It is not surprising, therefore, that the carbohydrates and their
metabolism have been the subject of comprehensive and in many respects successful
biochemical and medical research for a long time. While working on these problems,
Leloir made the discoveries for which he has now been awarded the Nobel Prize.
Before these discoveries were made,
our knowledge of carbohydrate biochemistry
was rather one-sided. The biological processes which break down carbohydrates,
including the so-called combustion, have been well known for several decades.
Over the years many Nobel Prizes have been awarded for chemistry and still more
for physiology or medicine for discoveries about the reactions and catalysts
involved. However, our knowledge about the innumerable corresponding synthetic
reactions which occur in all organisms, was fragmentary. We had to resort to
doubtful hypotheses; it was usually assumed that the syntheses were a direct
reversal of the well-known breakdown reactions. The work of Leloir has indeed
revolutionized our thinking about these problems.
In 1949 Leloir published the discovery which became the foundation for a remarkable
development. He found that in a certain reaction, which results in the transformation
of one sugar to another sugar, the participation of a so far unidentified substance
was essential. He isolated the substance and determined its chemical nature.
It turned out to be a compound of an unknown type, containing a sugar moiety
bound to a nucleotide. Compounds of this type are now called sugar nucleotides.
Leloir established that the transformation reaction does not occur in movie in Nobel Chemistry horse Prize sex the sugars
Chemistry Prize clip rape in Nobel original as Nobel Chemistry 8217 s lingerie men in Prize such, but Chemistry horse sex Prize in movie Nobel in the corresponding sugar nucleotides. To put it simply, one may
say, that the linking with the nucleotide occasions an activation of the sugar
moiety which makes the reaction possible.
The remarkable aspect of the discovery was not the explanation of a single reaction,
but Leloir's quick comprehension that he had
found the key which would enable
us to unravel an immense number of metabolic reactions. He ingeniously realized
that a path had been opened to a field of research containing an accumulation
of unsolved problems. In the twenty years that have elapsed since his initial
discovery he has carried on his research in this field in an admirable manner.
Other scientists were quick to grasp the fundamental importance of Leloir's
discovery; they realized that a vast field was now accessible to worth-while
scientific investigation and started research along the path which he had opened.
There can be no doubt that few discoveries have made such an impact on biochemical
research as those of Leloir. All over the world, his discoveries initiated research
work, the volume of which has grown over since. Leloir has been the forerunner
and guide throughout; he made all the primary discoveries which determined the
path and the objectives of the ensueing research work.
Leloir soon found that besides the sugar nucleotide first isolated, several
others of the same type occur in Nature, and many have also been found by other
research workers. Today more than one hundred sugar nucleotides which are essential
participants in various reactions are known and well characterized. Some of
them have an action similar to that of the first isolated, namely in the transformations
of simple sugars to other simple sugars or sugar derivatives.
Still more important was Leloir's discovery that other sugar nucleotides have
another action which occurs in the biological
synthesis of compounds which are
composed of or contain simple sugars or sugar derivatives. Leloir showed that
all these syntheses are essentially transfer reactions. Sugar moieties from
sugar nucleotides are transferred to accepting molecules which thereby increase
in size. Probably the most sensational discovery made by Leloir was that the
synthesis of thc high-molecular polysaccharides also functions in this manner.
The first example of the fundamental role of the sugar nucleotides in polysaccharide
biosynthesis was found by Leloir in 1959 in the case of glycogen. It became
clear that the polysaccharide biosynthesis is not a reversal of the biological
breakdown, as had doubtfully been assumed earlier. On the contrary, Nature uses
different and quite independent processes for synthesis and breakdown. Later
on the same extremely important principle was also shown to be valid with other
groups of substances, for instance with proteins and nucleic acids.
Through Leloir's work and the work of others, who were inspired by his discoveries,
knowledge of great significance has been gained in wide and important sections
of biochemistry, which were previously obscure.
It can be readily appreciated
that Leloir's work has also had far-reaching consequences in physiology and
medicine.
* The manuscript was read by Professor Arne Tiselius.
From Les Prix Nobel en 1970, Editor Wilhelm Odelberg, [Nobel Foundation], Stockholm, 1971
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