Proteins, genetically engineered

Moffat, A.S. (1991h). Plant pharmers" transform tobacco to prodnce proteins. Genetic Engineering News November/ December, 1 55. 

SiklosiT (2005). Manufacturing of biopharmaceutical proteins. Genetic Engin. News. 25(17) 58-59. 

Fusion proteins Genetically engineered proteins that are made by splicing together coding sequences from two or more genes. The resulting protein thus combines portions from two different parent proteins. 

The substrate specificity of an enzyme and its catalytic activity together result from the three-dimensional interaction of the substrate with the side chains of a few nicely positioned amino acids in the protein. Genetic engineering allows the nucleotide sequences coding for these amino acids to be altered as the DNA is transferred from one organism to another. Thus the amino acids which bind the substrate can be altered to accommodate new ones which are sterically excluded from the natural enzyme. The difficulty with this work is not so much the modification of the enzyme, but rather the purification and crystallization which are necessary to solve the three-dimensional structure in the first place. 

Biomedical Applications. TRIS AMINO is used for a number of purposes in its pure form, it is an acidimetric standard the USP grade can be utilized intraveneously for therapeutic control of blood acidosis TRIS AMINO also is useful in genetic engineering as a buffering agent for enzyme systems, industrial protein purification, and electrophoresis. AMP has found use as a reagent in enzyme-linked immunoassays. The primary appHcation is for alkaline phosphatase assays. 

Thaumatin. Thaumatin [53850-34-3] is a mixture of proteins extracted from the fmit of a West African plant, Thaumatococcus daniellii (Beimett) Benth. Work at Unilever showed that the aqueous extract contains two principal proteins thaumatin I and thaumatin II. Thaumatin I, mol wt 22,209, contains 207 amino acids in a single chain that is cross-linked with eight disulfide bridges. Thaumatin II has the same number of amino acids, but there are five sequence differences. Production of thaumatins via genetic engineering technology has been reported (99). 

Nucleic acids are the molecules of the genetic apparatus. They direct protein biosynthesis in the body and are the raw materials of genetic technology (see Genetic engineering). Most often polynucleotides are synthesized microbiologicaHy, or at least enzymatically, but chemical synthesis is possible. 

In 1989, two enzymes based on genetic engineering techniques were introduced, ie, a cloned alkaline protease (IBIS) and a protein engineered Subtihsin Novo (Genencor, California). Lipase and ceUulase types of detergent enzymes have also begun to appear. 

It is likely that any new enzymes isolated by screeners will be quickly and routinely cloned by genetic engineers, and be sequenced and expressed as almost pure proteins. Protein chemists can then evaluate the properties of the new enzyme and determine its three-dimensional stmcture. This vast amount of information allows the protein engineers and their computers to design the enzymes of the future. 

The extended ternary complex model can take into account the phenomenon of constitutive receptor activity. In genetically engineered systems where receptors can be expressed in high density, Costa and Herz [2] noted that high levels of receptor expression uncovered the existence of a population of spontaneously active receptors and that these receptors produce an elevated basal response in the system. The relevant factor is the ratio of receptors and G-proteins (i.e., elevated levels of receptor cannot yield constitutive activity in the absence of adequate amounts of G-protein, and vice versa). Constitutive activity (due to the [RaG] species) in the absence of ligand ([A] = 0) is expressed as... 

Recombinant DNA, this is DNA containing new genetic material in an order different from the original. Genetic engineering can be used to do this deliberately to produce new proteins in cells. 

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