Love egg whites or yolks? Translated into biochemical terms, do you prefer protein or fat?
Protein and fat are both good things, as long as they're in the right proportions and not in excess. Protein has a much better reputation than fat, and at least dieters don't mind it. However, when consumed in excess, excess protein will be converted to fat in the body, and the metabolized nitrogen-containing compounds will aggravate the burden on the kidneys.
The principle of health lies in moderation; the principle of the protein molecule lies in the art of behavior.
Egg white is mainly composed of protein, egg yolk is mainly composed of lecithin, lecithin is a kind of fat
Protein is the material basis of life, a variety of proteins division of labor, carrying most of the activities of life. Some as "bricks and mortar", building organisms; some "engage in transportation", itself as a carrier to transport other substances; some as "soldiers", and invasive pathogens combat; some open the "biochemical plant". "Biochemical factory", as an enzyme catalyzing a variety of biochemical reactions; some are "managers", as a hormone regulating a variety of physiological reactions; some as a "buffer", connective tissue, so that the body is flexible, and as a "body". The body is elastic, and as the "outer packaging" to protect the body, such as collagen in the skin; some are "messengers", in the cell-to-cell transfer of information ......
To fulfill these functions, proteins have to perform the art of behavior. Either folded, twisted, or entangled, they can't manifest these biological activities without twisting their bodies into a particular posture.
Protein molecules are miniature "yoga masters".
A protein is a "building"?
Fats are eaten raw or cooked, and they are fat molecules made up of fatty acids and cholesterol. Protein is different. Eaten raw, you eat a standing "building", cooked, you eat a collapsed "building". Frying and frying big fish and boiling and boiling and simmering big meats is not just about satisfying the appetites of foodies; if you think about it, you can see structural biology.
After food is cooked, the protein edifice collapses
Proteins are still proteins, and amino acid sequences are still sequences, but raw and cooked taste very different. This is because proteins are "denatured".
And this starts with the composition of the protein.
Proteins in living organisms are made up of more than 20 alpha-amino acids. Some proteins contain phosphorus, and others contain iodine, as well as metal ions such as iron, copper, zinc, manganese, cobalt, and molybdenum. The best feature of amino acids, the molecules have both basic amino groups (-NH2) and acidic carboxyl groups (-COOH). Plants can synthesize all the required amino acids by themselves, animals mention the amino acids, some of them are manufactured by themselves, and some of them have to be "imported", relying on food to obtain.
The same or different amino acids you out of an amino group, I out of a carboxyl group, to remove a water molecule, and then connected to a long chain, either branched or unbranched, is the peptide chain, different peptide chains assembled together, is the protein.
The sequence of amino acids is called the primary structure of proteins, and the "dance" of peptide chains is the secondary and tertiary structure of proteins, and the "collective dance" of peptide chains is the "dance" of proteins. The "collective dance" of the peptide chains is the "dance" of the protein, which is the fourth-level structure. Therefore, protein is a "building".
Structural composition of proteins
Proteins also practice "yoga"
The function of proteins is determined not only by the sequence of amino acids, but also by the "dance" of proteins.
Determining the function of proteins is not only the sequence of amino acids, but also the "dance" of the protein. In chemistry class, the teachers assembled molecular models are always hard, but in fact, many organic macromolecules are flexible, soft, can be twisted and folded and flipped to make a lot of difficult movements, like a "yoga" master.
Proteins are like "behavioral artists" in living organisms, and the flexibility of "yoga" is a prerequisite for their function. In biochemistry, these "yoga" is called protein folding, all kinds of folding together, composed of protein spatial conformation. For many biomolecules, spatial conformation is almost as important as structure. When meat and eggs are cooked, the amino acid sequence of the protein does not change, the peptide chain does not change, but the spatial conformation changes, and the properties and taste of the meat and eggs change, which is called the "denaturation" of the protein, i.e. the collapse of the spatial conformation. If you are burned or scalded, you will not be able to carry out your physiological functions even though your skin is still there.
Why do proteins practice "yoga" and why does a biomolecule place so much emphasis on "posture"? Proteins have normal physiological functions only when they are correctly folded. Once folded incorrectly, it will either be degraded or lose its activity, sometimes making people sick. Alzheimer's disease, which afflicts the elderly, is due to a change in protein conformation; cystic fibrosis is a failure of proteins to fold; familial hypercholesterolemia is a protein misfolding; and familial amyloidosis, a protein precipitation ......
Protein Misfolding, Sometimes Causes Disease
Proteins The higher structure of a protein is determined by the primary structure of the protein. Some people call this connection between primary structure and protein conformation the "second genetic code," and the importance of protein conformation can be seen from this.
Mutations in the amino acid sequence of proteins can change their conformation and function. For example, in sickle-shaped anemia, an amino acid is mutated. The two hemoglobin chains then "lock" together, eventually forming an insoluble bundle of long columnar helical fibers with the other hemoglobin chains***. As a result, the red blood cells are twisted into a sickle shape, which ultimately results in a decrease in the oxygen-carrying capacity of the red blood cells in the blood, leading to chronic hemolytic anemia in the patient. These diseases, in which a genetic mutation causes a molecular change in a protein, are called "molecular diseases.
Who is the "yoga" instructor for proteins?
Does protein folding happen randomly, or is there an underlying mechanism?
Some proteins fold automatically, without a "yoga" instructor, and are completely "self-taught".
The reversible denaturation of some small-molecule proteins in vitro is evidence of this. The "thermodynamic hypothesis" suggests that under certain circumstances, such as different solution components, pH, temperature and ionic strength, the polypeptide chains in proteins will automatically adjust their spatial position, as if the water is going to the lower part of the ground, so that the whole system is in the state of the lowest free energy, so that the structure of the protein is the most stable, the formation of the protein's conformation.
Sometimes, proteins need to be coached by "yoga coaches", who are called molecular chaperones or folding enzymes. Molecular chaperones and folding enzymes are proteins that help other proteins fold correctly, just like a coach teaching you the correct moves, and when they work, they bind to the proteins they are trying to help, separate from them when they are folded, and do not participate in the physiological functions of these proteins.
Protein "yoga array" and gossip have a spell
As the marching battle to pay attention to the formation, each battle victory can not be fully attributed to a single soldier, the same as the life function of protein is also "formation" results. "The result, so each protein should be tirelessly put to do "yoga", the amino acids in formation.
Hair keratin contains a large number of α-helix structure, hair has the elasticity; silk has a large number of β-helix, silk is soft and easy to stretch ...... compared to the amino acid sequence information, based on the conformation of the protein can often be more accurately predicted the function of the protein. Each physiological function is not always carried out in living cells, and various physiological functions have to be transformed over time and space, so it is necessary to "turn on" and "turn off" proteins, which are the executors of these functions. The conformation of proteins is not constant, but changes as functions are switched on and off.
Structural proteins, like "rebar", mostly fibrous; enzymes are a "matchmaker", mostly spherical, there is a small space inside, so that the organic material to be reacted to get together, close to the "talk about love! "; on the cell to bear the inside and outside of the cell material transportation "membrane protein" is to turn themselves into a busy traffic "tunnel" ......
From Square Dance to Latin Dance for All
If you know Latin dance, square dancing is not hard for you. Your yoga instructor will teach you different moves, and the same proteins will travel in different configurations, which is called "metamorphosis".
Who are the best students of metathesis? Hemoglobin and myoglobin. The main function of both proteins is to carry oxygen. Hemoglobin is in the blood and myoglobin is in muscle tissue.
Hemoglobin hides in red blood cells
No matter what the partial pressure of oxygen is, myoglobin always maintains a high affinity for oxygen molecules, embracing them intimately and never "disliking" them. Hemoglobin, however, behaves much differently due to the "metastable effect", and "dislikes" oxygen molecules. When the partial pressure of oxygen is low, the affinity with oxygen decreases, releasing oxygen and passing it to myoglobin; when the partial pressure of oxygen is high, hemoglobin is more than willing to carry as many oxygen molecules as it can. Why is this?
It turns out that the conformation of hemoglobin changes with the oxygen partial pressure. Human hemoglobin has four subunits. When the partial pressure of oxygen is high, the binding of one subunit to oxygen causes a change in the protein's conformation, allowing the other subunits to bind to oxygen more readily and more quickly. And when the partial pressure of oxygen is low, an oxygen molecule on one subunit detaches and drives more subunits to detach from the oxygen molecule, like the leader leading the flock, a phenomenon called positive synergism. Hemoglobin and myoglobin thus form an efficient mechanism for carrying oxygen molecules from the lungs to the muscles of the tissues.
Now that predicting protein structure has become a hot research topic in the life sciences, a new term, structural biology, has been coined. What is structural biology? It is the science of elucidating the phenomena of life and their applications based on the relationship between the specific spatial structure of biological macromolecules, the specific movement of the structure, and the biological function.
If you like origami, if you like folding napkins, if your hands are always able to make "yoga" out of ordinary objects, you may become a good structural biologist in the future.