What makes a protein

Structure and function of proteins

Proteins, Proteins or protein substances, are not only universal building and operating materials of all organisms, but also ensure that the metabolism works: they form the basis of the cell structure and act as biocatalysts (Enzymes) in metabolic reactions. They catalyze the synthesis of smaller molecules that either already have an independent function in the organism, such as vitamins, or are used as building blocks for macromolecules such as fats or carbohydrates. In addition, they also have a variety of other tasks, such as in the immune system in defense against infection or in the eye during the visual process. Proteins transport nutrients that are insoluble in water in the blood. The protein hemoglobin carries oxygen from the lungs to all tissues, especially the brain. Muscles are made up of the proteins myosin and actin. As structural proteins, collagen and keratin build up skin, hair and nails, as well as tendons and cartilage tissue.

Functional diversity of proteins

ProteinsfunctionExamples
EnzymesCatalysis of metabolic reactions in the organismFat splitting, sugar breakdown, nucleic acid build-up
Transport proteinsTransport of substances in the membrane and in body fluids, e.g. bloodHemoglobin (oxygen), transferrin (iron transport)
Immune proteinsDefense against infectionsantibody
Proteins that cause movementConversion of chemical into mechanical energyActin, myosin (muscle)
Regulator proteinsRegulation of metabolic processes; Switching genes on and offHormones
Receptor proteinsReceipt and transmission of stimuliRhodopsin (eye)
Structural proteinsSupporting substances in the organismCollagen for cartilage, bones, tendons; Keratin for hair; Nails, feathers


According to their diverse functions, proteins consist of up to 20 different building blocks, the amino acids. The amino acids are linked to one another in the proteins in different sequences and numbers. This results in 20 amino acids even for a relatively short chain length of 100 amino acids100 = 10130 theoretical possible combinations! The sequence and number of amino acids linked to form a protein determine the three-dimensional shape and function of a protein. This is due to the fact that the individual amino acids linked to form a chain interact with one another in a very specific way that obeys physico-chemical and chemical rules. This chain, which is made of 20 different types of pearls, can either form a thread-like structure, be folded or folded, twisted, or twisted into a ball or other structure - always depending on the sequence of the different pearls.

The proteins are made up of 20 different amino acids with different chemical properties. This results in an incredibly large number of possible combinations, which is reflected in the variety of proteins in form and function in plants, animals and humans.

The twenty amino acids used in nature to build protein
amino acidabbreviation(Three or one letter code)
AlanineAlaA.
ArginineArgR.
AsparagineAsnN
Aspartic acidAspD.
CysteineCysC.
GlutamineGlnQ
GlycineGlyG
HistidineHisH
IsoleucineIleI.
LeucineLeuL.
LysineLysK
MethionineMeadM.
PhenylalaninePheF.
ProlinePerP.
SerineSerS.
ThreonineThrT
TyrosineTyrE.
TryptophanTrpY
ValineValV.

There are very small proteins, so-called peptides, which are made up of only a few amino acids. These include, for example, some hormones. Other proteins consist of several hundred amino acids. The information about the number and the sequence of the amino acids for each individual protein of an organism is stored in the DNA. The unit of information in DNA, which determines the number and sequence of amino acids in a particular protein, is called a gene - or, more simply: a gene contains the information required to synthesize a protein from amino acids.

Source:BLL