Synthesis from amino acids

One suggestive piece of support that leads to the idea that certain different RNA informed pathways of protein synthesis from amino acids arose in different vesicles is the correlation between the different first and, to some degree, the second... 

Preparative applications of these reactions have included work on peptide synthesis from amino-acids (suitably protected) using triphenyl phosphine (120)10 7 >108 or a polymer-bound aryldiphenylphosphine (128).109 Coupling is generally very efficient,107 but racemization problems occur in some reactions.108 109 A typical coupling reaction using (128) is outlined in Scheme 9. 

It is important to appreciate that this principle of coupling-in-series underlies all biochemical pathways or processes, e.g. glycolysis, generation of ATP in the mitochondrion, protein synthesis from amino acids or a signal transduction pathway. Indeed, despite the fundamental importance of signalling pathways in biochemistry, a thermodynamic analysis of such a pathway has never been done, but the principles outlined above must apply even to signalling pathways. 

With the exception of doxycycline and minocycline, tetracyclines inhibit to some extend protein synthesis from amino acids also in mammalian cells. This antianabolic effect is reflected by raised blood urea levels in the patient. 

Due to the vast numbers and rapidity of novel developments in solid-phase synthesis over the past ten years, a number of reports currently found in the literature deal with solid-phase syntheses of lanthionine peptides. There are at least two different approaches to synthesize lanthionine peptides in which the sulfide bond links amino acid halves that are not direct neighbors within the peptide chain (Scheme 10). One obvious approach, method A, is based on the coupling of a preformed, orthogonally protected lanthionine monomer to the N-terminus of a peptide oxime resin. 48 This is then followed by acid-catalyzed cyclization and simultaneous release from the resin during amide bond formation with the C-terminal carboxy group via the peptide cyclization method on oxime resin (see Section 6.73.2.2). The alternative approach is lanthionine formation after peptide synthesis from amino acid derivatives, such as serine and cysteine (method B). 

Protein synthesis Glycogen synthesis Lactate uptake Amino acid uptake Glutaminase Glycine oxidation Ketoisocaproate oxidation Acetyl-CoA carboxylase Urea synthesis from amino acids Glutathione (GSH) efflux Taurocholate excretion into bile Actin polymerization Microtubule stability Lysosomal pH... 

Figure 10-1. Enzymatic pathways for glucose synthesis from amino acids or pyruvate in mammalian Ever. Enclosed in the boxes are the glucogenic amino acids with arrows indicating the points where carbon skeletons from these amino acids enter the pathways of gluconeogenesis or the tricarboxylic acid cycle. Bracketed next to the rate-controlling enzymes for gluconeogenesis are some of the substances that increase (T) or decrease (1) the activity of these enzymes. 3PG, 3-phosphoglycerate.

The effects of cortisol on gene transcription are usually synergistic to those of certain other hormones. For instance, the rates of gene transcription for some of the enzymes in the pathway for glucose synthesis from amino acids (gluconeogenesis) are induced by glucagon as well as by cortisol. 

Synthesis from amino acid and common metabolic precursors usually occurs in the cytoplasm of the presynaptic nerve terminal. The synthetic enzymes are transported by fast axonal transport from the cell body, where they are synthesized, to the presynaptic terminal. 

Figure 18.10 Schematic representation of ATP synthesis and coupied reactions in iiving systems. The conversion of giucose to carbon dioxide and water during metaboiism reieases free energy. The reieased free energy is used to convert ADP into ATP. The ATP moiecuies are then used as an energy source to drive unfavorabie reactions, such as protein synthesis from amino acids.

Symbols velocity constant of A<-LDH protein synthesis from amino acids ... 

Peptide Synthesis from Amino Acid Esters. 194... 

The mitochondria are parts of a cell that obtain energy in the form of ATP from glucose (from food), C6Hi20g. ATP molecules are used in various cell processes, such as protein synthesis from amino acids, which occurs in the ribosomes. 

By its very nature, the process of chemical bond formation between hyaluronan maao-molecules and organic compounds under the joint action of pressure and plastic deformation is similar to the reaction of polypeptide synthesis from amino acids or polysaccharides formed from simple sugar. The formation of chemical bonds can be visualized as a joining of -OH, -COOH and -NH groups accompanied by removal of the water molecule. However, in aqueous mediums, equilibrium of this type of reaction is shifted towards parent substances rather than the products of the reaction. Therefore, such reactions, both in living systems and under laboratory conditions, are achieved as a result of a complex multistage process, far from being similar to a simple process of water removal. The proposed solid-phase... 

ATP is involved in the synthesis of hippuric acid and its analogs. In the case of hippuric acid, and very probably of its analogs, the role of ATP is to form the aromatic acyl-Co A, which then condenses with glycine to form the quasi-peptide. But in the synthesis of glutamine from glutamic acid and ammonia Co A is not required, ATP is. And in the synthesis of glutathione, the one case so far elucidated of an enzymatic peptide synthesis from amino acids, again Co A appears not to be required, while ATP is. 

Within the islets of Langerhans, insulin is synthesized from the precursor polypeptide proinsulin. We will study polypeptide synthesis from amino acid building blocks, followed by protein synthesis from the polypeptide chains, with the example of insulin. 

---