Chemistry

Enzyme regulation

Enzyme regulation



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Serine protease inhibitors

The reaction with diisopropyl fluorophosphate (DIPF) is considered a diagnostic test for the presence of an active serine residue in serine proteases such as chymotrypsin or acetylcholine esterase. The enzyme is irreversibly inhibited because DIPF has a tetrahedral phosphate group, which is an analogue to the transition state in catalysis and thus occupies the space for the substrate. Due to the organic phosphate group and its irreversible inhibitory effect on acetylcholine esterase, DIPF acts as a strong neurotoxin.


Welcome to chemistry

Here you will find a learning sheet for almost all chemistry topics. This includes topics such as organic chemistry with alkanes, alkanals, alkanoic acids and the like, inorganic chemistry with the structure of metals and other groups of substances, and calculations of volume, density or amount of substance. There are not many learning slips online for chemistry yet, but several more learning slips are already in the middle of production. The learning sheets are great for preparing yourself for exams.
In addition, there are explanations with interactive animations on the websites with the respective online view of the learning sheet. Most of the animations are also available in image format and can be downloaded individually from the image gallery.
These pictures are also available for presentations, documentary work, posters, presentations and everything else.
Have fun with a delicious ice cream!


Biology online

In this module, an overview is given of the division of living beings into eukaryotes and prokaryotes, the differences, similarities and development history, the cell structure, the cell organelles and their function. Then it goes straight to the molecular level of biology, where we discuss the molecules of life, their chemical structure and their functions. Genetics, which will be covered next, is a very complex topic that is given a lot of time. First, Mendel's rules are discussed. Then it goes to the molecular level of genetics, where the DNA and the chromosomes or the different forms of cell nucleus division (mitosis and meiosis), the cell cycle and replication or the possible errors in DNA replication and their repair mechanisms are discussed. This knowledge makes it possible to understand genetic engineering processes such as the polymerase chain reaction (PCR) and cloning and to understand protein biosynthesis. Afterwards, important energy metabolism processes such as glycolysis, citrate cycle and respiratory chain, as well as their location in the cell, are discussed. In particular, the regulation by enzymes is discussed. The basics of the immune system, what blood cells there are and what function they take on in the defense against bacteria and viruses, we will clarify in the last block of this day. On the last day we deal with the transmission of signals in the body. The most important hormones and hormone systems are explained together with the organs responsible for them and then the rapid signal transmission through nerve conduction is dealt with. At the end of the course, the evolution theories of Lamarck and Darwin are dealt with.

day 1 day 2 Day 3 Day 4 Day 5
09:00-10:30 Cytology I: overview, cell structure Classical Genetics I Cell cycle Protein synthesis Hormones I.
10:45-12:15 Cytology II: cell organelles Classical Genetics II Replication Intermediate metabolism Hormones II
13:15-14:45 Molecules of Life I: Carbohydrates and Amino Acids Molecular Genetics: DNA and Chromosomes DNA repair mechanisms Enzymatic reactions and regulatory principles Nerve conduction
15:00-16:30 Molecules of Life II: Lipids and Nucleic Acids Cell division: mitosis, meiosis Genetic engineering Microbiology, immune system evolution

Your course goals


Albert Einstein

He was one of the most important physicists in history and the founder of the theory of relativity, which led to a complete change in the physical worldview. In addition, he performed fundamental work in many areas of physics. In particular, he interpreted the photoelectric effect and was thus one of the founders of quantum theory. In his doctoral thesis he theoretically explained the Brownian molecular motion of particles and thus contributed to the implementation of atomic theory in chemistry. His advocacy of humanity and the responsible use of physical knowledge should be emphasized.

These theories led to a complete change in the physical worldview. His work is comparable to that of KOPERNIKUS, GALILEI or NEWTON.


Sub-areas of chemistry

Even a cursory glance at our surroundings shows us the everyday presence of chemical processes and structures: Every food we eat consists of different substances or mixtures of substances in our body, various changes take place, which require the loosening and forming of new chemical bonds. Almost all objects that surround us are linked to chemical processes in their creation, be it a metallic object, a plastic, a building material or a color. Our individual mobility is based on chemical processes that provide us with the energy to move. If we use a means of transport, in most cases chemical energy is converted into mechanical energy. If we have to reach for drugs, their production and mode of action are linked to chemical structures and reactions. Yes, even reading this text is not possible without chemical changes in the eye and within the brain.

Physical, chemical and biological processes have taken place in nature since prehistoric times, long before humans and the sciences they created existed. With their help, humans recognized the interrelationships of nature and were increasingly able to use chemical processes to improve their livelihoods.
The modern natural sciences often research and describe the same objects from different perspectives. Nature includes all material objects, structures and processes in the infinite variety of their manifestations. This fact gives rise to two important points: firstly, it is not possible to make an absolute distinction between the natural sciences; secondly, research into an object often requires the cooperative interaction of different sciences. Nevertheless, every science has its specifics - so does chemistry .

The natural science of chemistry studies the structure, properties and transformation of substances, in particular the material and energetic changes that are associated with the dissolution and formation of new chemical bonds.

In the historical development of chemical science and the increasingly clear complexity of the interrelationships, different sub-areas with (relatively) independent areas of investigation and application were broken down, which, however, can never fully describe an object on their own (Fig. 1):

  • Inorganic chemistry
  • Organic chemistry
  • Theoretical (general chemistry)
  • Physical chemistry
  • Electrochemistry
  • Preparative chemistry
  • Analytical chemistry
  • biochemistry
  • technical chemistry
  • Environmental chemistry
  • Materials chemistry
  • Complex chemistry.

In the course of time, different areas of chemistry emerged. A strict demarcation between the related disciplines is just as impossible as the strict separation of chemistry from the other natural sciences. The disciplines of thermodynamics, kinetics, electrochemistry, theoretical and nuclear chemistry are also summarized under the heading of physical chemistry. The sub-areas of chemistry are also not clearly defined. One could e.g. B. also include photochemistry, fluorine chemistry, etc. as relatively independent areas.


Enzyme regulation tasks

In general, you can query very dull material:

With which type of enzyme inhibition can the following changes in the Michaelis-Menten values ​​Km and Vmax be expected?

a) Vmax remains constant, Km is increased
b) Vmax and Km are decreased

or refer to a topic that may have been discussed in:

Benzamidine is a competitive inhibitor for trypsin, which catalyzes the hydrolysis of peptide bonds (arginine, lysine residue). Please sketch and describe the different course of the curve with regard to an uncompetitive escapement in a Michaelis-Menten diagram. Also go into Km and Vmax explicitly and explain why the different values ​​came about.


It is true, but it is wrong that the operon model has nothing to do with enzyme regulation.

It has something to do with enzyme regulation, because I don't know any operon that is constitutively expressed. The expression of the genes in an operon is regulated as required. In the operon, this usually happens via the 2 different mechanisms mentioned by noir:
Substrate induction (e.g. lac operon) or substrate repression (e.g. tryptophan operon).

Besides the two, there are many other mechanisms by which gene expression can be regulated. The operon model only applies to prokaryotes and not to eukaryotes, since there are no operons there.
In general, however, one can differentiate between prokaryotic and eukaryotic mechanisms. There are also mechanisms that exist with both forms.

Regulation can also take place on many different levels. In eukaryotes there are particularly many possibilities for regulation, since their expression machinery is significantly more complicated and contains many more steps than in prokaryotes.
Different possibilities with eukayrots:
- Arrangement of the histones in the chromatin
- alternative splicing
- RNA editing
- Antisense RNA (RNA interference)
- folding of proteins
- Control of the mRNA, before the core export


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Description Enzyme regulation through enzyme modification

An orderly metabolism can only take place through controlled enzyme activity. A key mechanism here is the regulation of key metabolic enzymes. Key enzymes are, for example, at the beginning of a metabolic pathway. The activity of the enzyme is controlled by chemically changing certain amino acid groups. A chemical change in certain amino acid groups also changes the spatial enzyme structure with consequences for the ability to bind substrate. A chemical change in the amino acid groups can be permanent (irreversible) or reversible (reversible).

Transcript Enzyme regulation through enzyme modification

The topic of this unit is the regulation of enzymes. There are two main levels of regulation for the regulation of enzymes. On the one hand, the amount of enzyme formed can be regulated at the protein biosynthesis level. On the other hand, the activity of already formed enzymes can be regulated by modifying the enzymes, i.e. changing them. This mechanism has the advantage over the first that it runs much faster and can therefore react differently to changes. In the following we will deal exclusively with the level of regulation of enzyme modification. Before we look at the different possibilities of regulation, we still have to clarify why enzymes have to be regulated. If we look at the metabolism of organisms, the enzymes are the crossroads. Without regulation, the metabolism would collapse. As an analogy, we can see the maintenance of regulated traffic through traffic light signals. In addition, a general aspect of enzyme regulation: the question of how metabolic pathways are regulated. The constant force of selection means that only the best-adapted blueprints are retained. In the case of the regulation of metabolic pathways, this means that not all enzymes in a metabolic chain are regulated, but only a few key enzymes. With this prior knowledge, we can now take a closer look at enzyme regulation. Enzymes can be regulated reversibly or irreversibly. In the first case this means that the change in the enzyme is not permanent, whereas in the second case the change in the enzyme is permanent. In the case of reversible enzyme regulation, we can differentiate between competitive and non-competitive inhibitors. In the case of non-competitive regulation, there are also effectors that have an activating effect on the enzyme activity. Let's give competitive inhibition a face. Our well-known enzyme binds a substrate in the area of ​​the active center and converts it. A competitive inhibitor is similar to the substrate and binds to precisely this point on the enzyme. The difference is: it cannot be converted by the enzyme and thus blocks the active center of the enzyme. However, if the substrate concentration increases, the competitive inhibitor is displaced. So substrate and inhibitor compete for the active site of the enzyme. A therapeutically important aspect of the competitive inhibitors is their dose-response relationship. Atropine, an alkaloid from deadly nightshade, for example, is an inhibitor of acetylcholinesterase. Administered in small doses it has therapeutic benefits, but in excessive doses the effects are negative. So it would be wrong to call the substance a poison on its own. It continues with non-competitive inhibitors. As already mentioned, there are also positive effectors. A term analogous to non-competitive regulation is allosteric regulation. In contrast to competitive inhibition, the effector does not bind in the area of ​​the active center, but at another point of the enzyme, the allosteric center. The effector also bears no resemblance to the substrate. The binding of an effector changes the spatial structure of the enzyme and thus also its activity. In contrast to competitive inhibition, the inhibitor is not displaced by an increasing substrate concentration. The irreversible enzyme regulation differs fundamentally from the reversible regulation mechanisms already discussed. A covalent bond between the enzyme and the irreversible inhibitor permanently changes the spatial structure of the enzyme. It also loses its catalytic abilities as a result. In this case, too, we can speak of poisons, but their toxic effect is much more potent than in the first case of reversible competitive inhibition.


Studies and first professional steps

EINSTEIN tried to study engineering in Switzerland, but failed the entrance exam at the Zurich Polytechnic due to a lack of foreign language skills. After completing his Abitur at the canton school in Aarau, EINSTEIN studied physics in Zurich from 1896 to 1900 and passed the exam as a physics teacher.

He then worked for several years as an expert at the Office for Intellectual Property (Patent Office) in Bern. This activity gave him a lot of time to deal with physical problems. He referred to himself as "Patentierknecht", since in his work he inter alia had to examine submitted patents. For EINSTEIN, this time in Bern was the happiest and most scientifically fruitful of his life.