Proteins are subdivided into two major groups:
a) simple proteins (Greek: prótos — primary) composed only of amino
acids. Such are the albumins, globulins, histones, glutamins, prolamins, etc.
Of special interest here are the histones and protamins which take part
into complicated interrelationships with the nucleic acids in the processes of
protein synthesis and transfer of hereditary information in the
chromosomes, that is why they will be mentioned again in the next Section.
image
Figure 2–29. The twenty amino acids which participate in the building of proteins. All of them are L-forms.
b) complex — proteids, incorporating in themselves other components
except amino acids. Such are the glycoproteids (+ carbohydrates),
nucleoproteids (+ nucleic acids), lipoproteids (+ lipids), phosphoproteids
(+ phosphoric acids) and chromoproteids (+ pigments with groups
containing metals).