ABSTRACT
This chapter presents the basic principles for the biosynthesis of the primary structure of proteins, which allow for the versatile feature of biotechnology. The genetic information coding for the biosynthesis of an individual protein is called a structural gene. In eukaryotes, the entire structural gene is transcribed from the deoxyribonucleic acid to produce nuclear precursor messenger ribonucleic acid (pre-mRNA) and then "processed" into mRNA. In prokaryotes, biosynthesis is initiated with transfer RNA fMet, which is acylated with N-formylmethionine, rather than with methionine. Prokaryotes have a high internal reducing environment which may not allow disulfide bond formation. Disulfide bond formation constitutes a common and essential posttranslational event. An additional complication with respect to protein glycosylation is the strong evidence that the glycoproteins with identical primary structure are glycosylated differently if they are made by cells in different parts of the body. Numerous modifications can occur posttranslationally in the biosynthesis of proteins.
