Principles of Biochemistry, Volume 3 - A. Lehninger 1985

Molecular Mechanisms of Genetic Information Transfer
More on Genes: Repair, Mutation, Recombination, and Cloning
The study of recombinant DNA is of great practical importance

The Cloning of recombinant genes and their expression to produce protein products in E. coli and Yeast Cells, which can be cultivated on a massive scale, enables the industrial manufacturing of many valuable Proteins that are otherwise extremely difficult to obtain in large quantities. The Prospects of utilizing recombinant DNA have given rise to a new branch of molecular biology: Introduction/32.html">Genetic Engineering.

A simple example is the bacterial enzyme DNA ligase, which has proved invaluable in Gene biochemistry research. This enzyme is produced in large quantities by E. coli cells engineered with multiple extra copies of the DNA ligase gene. The yield of DNA ligase from such cells is several hundredfold higher than that of normal cells. By cloning additional copies of genes into E. coli and yeast, very large amounts of many other industrially important Enzymes can be obtained. Another triumph of genetic engineering is the introduction of genes capable of oxidizing petroleum Hydrocarbons into a common, harmless bacterium; such a bacterium can be deployed in the cleanup of oil spills.

Genes for A number of medically crucial proteins have been successfully cloned. Insulin, essential for the Treatment of diabetes, is currently harvested from the pancreases of slaughtered livestock. Although this animal insulin meets current demands, the rising incidence of diabetes—affecting over 5% of the population in the USA—means that demand may eventually outstrip supply. Furthermore, animal insulin is not identical in its Amino Acid Sequence to human insulin, rendering it ineffective or even allergenic for certain individuals. Recently, researchers succeeded in inducing E. coli to synthesize human insulin by introducing the corresponding gene. This synthetically produced human insulin is already in clinical use for diabetes treatment. Similarly, Recombinant DNA technology has made it possible to utilize pituitary Growth Hormone (somatotropin), previously unavailable for medical Applications. This is vital because animal growth Hormones are ineffective in treating human dwarfism due to differences in the Amino acid sequences of Human and Animal somatotropin.

Cells carrying the appropriate cloned genes can also yield high quantities of diverse proteins valuable in agriculture. For instance, genetic engineering techniques have been employed to develop a novel, highly effective vaccine against FOOT-and-Mouth disease in cattle, sheep, and pigs. This viral disease is incurable, and infected animals become unfit for consumption. In the developing world, foot-and-mouth disease is endemic, causing massive economic devastation and human hardship. The vaccine was produced utilizing a cloned protein antigen of the foot-and-mouth disease virus. Another critical objective is the introduction of genes encoding enzymes and other proteins involved in Nitrogen Fixation into the genomes of crop plants that naturally lack nitrogen-fixing capabilities. While Structure/179.html">Practical Applications are still some distance away, it is evident that achieving this goal will have a profound impact on global agriculture.