What kind of isomers can amino acids form? Which isomer is present in most living organisms?
don't major compounds of living organisms consist of modifications of hydrocarbons
Although D amino acids can be found in nature, only the L isomers are used to form proteins. The D isomers are most often found attached to the cell walls of bacteria and in antibiotics that attack bacteria. The presence of these D isomers protects the bacteria from enzymes the host organism uses to protect itself from bacterial infection by hydrolyzing the proteins in the bacterial cell wall.
Source:
http://chemed.chem.purdue.edu/genchem/topicreview/bp/1biochem/amino2.html
Amino acids can form two main types of isomers: D and L isomers. These isomers refer to the arrangement of atoms around a chiral carbon, which is a carbon atom that is bonded to four different groups or atoms.
In the case of amino acids, the chiral carbon is the α-carbon, which is the carbon atom that is directly bonded to the amino group, the carboxyl group, a hydrogen atom, and a side chain or R-group. The D and L isomers differ in the spatial arrangement of these groups around the chiral carbon.
In most living organisms, the L isomers of amino acids are predominantly used in protein synthesis. Proteins are made up of chains of amino acids joined together by peptide bonds. The specific sequence of amino acids determines the structure and function of the protein.
D amino acids can be found in nature, but they are not commonly used in protein synthesis in most living organisms. However, D isomers are often found attached to the cell walls of bacteria and in certain antibiotics that target bacteria. The presence of D isomers in bacteria helps protect them from enzymes in the host organism that would otherwise break down the bacterial cell wall.
It is important to note that while major compounds in living organisms do consist of modifications of hydrocarbons, such as lipids and carbohydrates, amino acids are the building blocks of proteins, which are crucial for various biological processes.