which one is standard amino acids L or D form
The standard amino acids found in proteins are in the L-form. The D-form of amino acids is less common and is typically found in certain bacteria, peptides, and antibiotics.
In biochemistry, standard amino acids are typically found in the L form. The L and D forms refer to the configuration around the asymmetric carbon atom in the amino acid molecule. The L-form amino acids have the amino group on the left side, while the D-form amino acids have the amino group on the right side. In proteins, almost all amino acids are in the L form.
The standard amino acids in proteins vary, but they are almost always in the L-form. In general, amino acids exist in two forms: L (levo) and D (dextro). These terms refer to the spatial arrangement of their atoms. In biochemistry, the L-form is predominantly found because it corresponds to the configuration in natural proteins.
To determine whether a specific amino acid is in the L or D form, you can look at its molecular structure. In the L-form, the amino group (-NH₂) is on the left side, while the carboxyl group (-COOH) is on the right side when the molecule is drawn in a Fischer projection. In the D-form, the arrangement is opposite, with the amino group on the right and the carboxyl group on the left.
It's important to note that there are some exceptions, and some non-standard amino acids can be found in the D-form in certain organisms or specific contexts. However, for the standard 20 amino acids found in proteins, the L-form is the most common.