COVID-19: The Chemistry of a Virus

Most viruses consist of three components: the genetic material, some proteins and a lipid layer.  In the case of SARS-Cov-2 (the virus responsible for the Covid-19 disease) the genetic material is a 30,000 repeat unit RNA, some of its proteins bind to, and protect, this RNA whilst others act as spikes to anchor to human cells and the lipid layer acts to protect the whole assembly.

The genetic material is either DNA or RNA and acts as the instruction set.  DNA is the famous double helix of nucleotide base pairs.  The RNA is a single strand of the same chemistry.  SARS-Cov-2 consists of about 30,000 nucleotides repeat units in a single strand. It was sequenced early on.

Proteins, or polypeptides, are polymers of amino acids.  In all proteins, the stereochemistry of different amino acids, combined with the hydrogen bonding between different amino acids, often quite displaced along the chain, causes them to fold into specific shapes.  They sometimes function as catalysts to drive the chemical reactions that power biology, or they can act as one half of a lock and key attachment mechanism. 

The infamous “spikes” on the coronavirus are made this way – they are the right size and shape to latch onto the ACE-2 (angiotensin-converting enzyme 2) receptor attached to the outer surface of cells in the lungs (specifically the pneumocytes type 1 cells that make up the lining of the lungs), arteries, heart, kidney, and intestines. Once attached, the genetic material is moved into the cell and takes over its replication system – producing many copies of the virus. It is relevant to note that since ACE-2 manages blood pressure by catalysing the cleavage of angiotensin II into angiotensin, when patients with high blood pressure get Covid-19, this interference in the activity of ACE-2 means they are more affected by the virus.

Lipid layers are built from surfactants (surface active chemicals) – one end is hydrophilic, and the other end is oleophilic (or hydrophobic).  When dispersed in water above a particular concentration, the oleophilic ends cluster together and form vesicles or sheets.  These vesicles make up the “bags” that cells use as containers.  The same is true of viruses – the lipid layer acts as a protection against the environment