Слайд 2Folding. What is it?
In biochemistry and molecular biology, protein folding is
the process of spontaneous folding of a polypeptide chain into a unique native spatial structure.
Each protein molecule begins to form as a polypeptide translated from the mRNA sequence in the form of a linear chain of amino acids. The polypeptide does not have a stable three-dimensional structure (example on the left side of the image).
Слайд 3Chaperones
To ensure folding, a group of auxiliary proteins called chaperones is
used. They prevent the interaction of newly synthesized proteins with each other, isolate the hydrophobic portions of proteins from the cytoplasm and "remove" them inside the molecule, the protein domains are correctly positioned.
Слайд 4Fundamental problems of folding
The problem is that humanity, with all its
computing power and an arsenal of experimental data, still has not learned how to build models that describe the process of protein folding and predict the three-dimensional structure of a protein based on its primary structure (i.e. amino acid sequence). Thus, there is still no full understanding of this physical process.
Слайд 5What is being done to solve the problem?
There are two groups
of structure prediction methods:
The first includes the so-called modeling methods “from scratch”
The second group of methods includes comparative modeling methods.
Слайд 6Coagulation mechanisms of protein molecules
Coagulation of the polypeptide chain into the
native conformation is most successful under physiological conditions. The loss of native conformation, denaturation, occurs at extreme pH, high temperature or under the influence of organic solvents, detergents and other denaturing substances.
Слайд 7Examples
Consider a few examples, globular proteins built from α-helices, such as
myoglobin, are rare. Usually there are combinations of folded sheets and spiral sections, such as, for example, in flavodoxin, a small flavoprotein, where 5 fan-folded sheets of five parallel strands form the nucleus of the molecule; 4 α-helical regions surround the core from the outside. Immunoglobulin is constructed from several similar domains (independent, compactly folded fragments of the polypeptide chain) in which two antiparallel folded sheets of three or four strands form a barrel-shaped structure.The oligonucleotide shown in the diagram shows the CH2 domain.