Hydrogen bonding is an interaction between molecules that resembles Van der Waals interactions and occurs in the human body. The bond plays a role primarily in the context of peptide bonds and chains of amino acids in proteins. Without hydrogen bonding ability, an organism is not viable because it lacks vital amino acids.
What is hydrogen bonding?
Hydrogen bonds are intermolecular forces. Without their existence, water would not exist in different states of aggregation, but would be gaseous. Hydrogen bonding is abbreviated as hydrogen bonding or H-bonding. It is a chemical effect that refers to the attractive interaction of covalently bonded hydrogen atoms on free electron pairs of an atomic grouping atom. The interaction is based on polarity and, more precisely described, exists between the positively polarized hydrogen atoms in an amino or hydroxyl group and free electron pairs of other functional groups. Only under certain conditions does the interaction occur. One condition is the electronegative property of the free electron pairs. This property must be stronger than the electronegative property of the hydrogen to create a strong bond. The hydrogen atom can thus be polar bonded. Electronegative free atoms can be, for example, nitrogen, oxygen, and fluorine. Hydrogen bonds are secondary valence bonds whose strength is usually far below that of covalent bonds or ionic bonds. Molecules in hydrogen bonds have a relatively high melting point relative to their molar mass and a similarly high boiling point. The bonds have medical relevance primarily with respect to the peptides and nucleic acids within an organism. Hydrogen bonds are intermolecular forces. Without their existence, water would not exist in different states of aggregation, but would be gaseous.
Function and task
Hydrogen bonding has only weak interaction and occurs between two particles or within molecules. In this context, the bond form plays a role, for example, in the formation of tertiary structures in proteins. In biochemistry, protein structure refers to the different structural levels of a protein or peptide. The structures of these naturally occurring substances are divided hierarchically into a primary structure, a secondary structure, a tertiary structure and a quaternary structure. The primary structure is considered to be the amino acid sequence. When a protein is mentioned in terms of spatial arrangement, there is often talk of protein conformations and the phenomenon of conformational change. Conformational change in this context corresponds to a change in spatial structure. The arrangement of proteins has the peptide bond as its basis. This type of bond always connects amino acids in the same way. In cells, peptide bonds are mediated by ribosomes. Each peptide bond corresponds to a connection of carboxyl groups of one amino acid and amino groups of a second amino acid, which is accompanied by the splitting off of water. This process is also known as hydrolysis. In each peptide bond, a single bond connects a C=O group to an NH group. The nitrogen atom has exactly one free electron pair. Because of the high electronegativity of oxygen, this free pair is under the electron-withdrawing influence of O2 atoms. In this way, the oxygen partially pulls the free electron pair into the bond between the nitrogen atom and the carbon atom, and the peptide bond acquires proportional double bond character. The double bond character removes the free rotatability of the NH and C=O group. Oxygen atoms and hydrogen atoms of peptide bonds are relevant for the structure formation of all peptides and proteins without exception. Two amino acids can attach to each other in this way. After such an attachment, all peptide bonds of two chains of amino acids are directly opposite each other. The hydrogen atoms in the peptide bond are relatively positively polarized when compared with the oxygen atoms of the peptide bonds directly opposite each other. In this way, hydrogen bonds form and connect the two amino acid chains together. All amino acids in the human body are organic compounds consisting of at least one carboxy group and one amino group.Amino acids are an essential structural building block of human life. In addition to the α-amino acids of proteins, more than 400 non-proteinogenic amino acids with biological functions are known that could not be formed without hydrogen bonding. Forces such as hydrogen bonding thus primarily stabilize the tertiary structure of amino acids.
Diseases and disorders
When there is a disturbance in the formation of functional protein gene spatial structures, the term protein folding disease is usually used. One such disorder is Huntington’s disease. This genetic disease is inherited in an autosomal dominant manner and is due to a genetic mutation in chromosome 4. The mutation leads to instability of the gene product. The disorder is a neurological disease associated primarily with involuntary hyperkineses of the distal extremities and face. Persistent hyperkineses result in rigidity in the affected muscles. In addition, patients of the disease suffer from increased energy expenditure. Pathological phenomena related to hydrogen bonding or general protein structure are also present in prion diseases such as mad cow disease. According to the most widely accepted hypothesis, BSE initiates protein misfolding. These misfolded proteins cannot be degraded by physiological processes and therefore accumulate in tissues, especially in the central nervous system. The result is degeneration of the nerve cells. Malformations of the protein structure are also discussed in the causal context of Alzheimer’s disease. The diseases mentioned do not directly affect hydrogen bonding, but refer to the spatial structure of proteins, to which hydrogen bonding contributes significantly. An organism with an absolute inability to hydrogen bond is not viable. A mutation causing this would result in an early gestational decline.
