Catabolic and anabolic are two different states that describe whether the body is building tissue or breaking it down. When you're trying to gain weight, you want to maximize the time your body is in a building state so that you can get bigger, stronger and see improvements in your performance. The way you eat, train and rest can affect the rate at which you'll see these improvements.
Ignoring tyrosine (as it's immediate precursor is phenylalanine, an essentialamino acid), all of the nonessential amino acids (and we will include argininehere) are synthesized from intermediates of major metabolicpathways. Furthermore, the carbon skeletons of these amino acids are traceableto their corresponding ketoacids. Therefore, it could be possible tosynthesize any one of the nonessential amino acids directly by transaminatingits corresponding -ketoacid, if that ketoacid exists as a commonintermediate.
So, the synthesis of asparagine is intrinsically tied to that of glutamine,and it turns out that glutamine is the amino group donor in the formation ofnumerous biosynthetic products, as well as being a storage form of NH3. Therefore, one would expect that glutamine synthetase, the enzyme responsiblefor the amidation of glutamate, plays a central role in the regulation ofnitrogen metabolism. We will now look into this control in more detail, beforeproceeding to the biosynthesis of the remaining nonessential amino acids.
Cellular Respiration - uses oxygen from the environment and converts each pyruvate to three molecules of carbon dioxide while trapping the energy released in this process in ATP. There are 3 sub-pathways of cellular respiration - pyruvate oxidation, the citric acid (Krebs or Tricarboxylic Acid) cycle and the electron transport chain. Occurs in different sub-compartments of mitochondria.
The word tannin is very old and reflects a traditional technology. "Tanning" (waterproofing and preserving) was the word used to describe the process of transforming animal hides into leather by using plant extracts from different plant parts of different plant species.
We will consider one important step in the synthesis of this group of 3 aminoacids, namely the step in which homocysteine is converted to methionine,catalyzed by the enzyme :
We used a population-based case-control study of breast cancer by age 50 in southern Germany to evaluate the association between dietary intake of different phytoestrogens and premenopausal breast cancer risk.
has 3 isozymes of aspartokinase that respond differently toeach of the 3 amino acids, with regard to enzyme inhibition and feedbackinhibition. The biosynthesis of lysine, methionine and threonine are not, then,controlled as a group.
These are the "branched chain" amino acids, and it's helpful toremember them as a group, not only because they all originate from the pyruvate carbonskeleton, but also because the disease "maple syrup urine disease" (MSUD)is a result of deficiency of branched-chain -ketoaciddehydrogenase, resulting in a buildup of branched-chain -ketoacids.
Asparagine and glutamine are the products of amidations of aspartate andglutamate, respectively. Thus, asparagine and glutamine, and the remainingnonessential amino acids are not directly the result of transamination of -ketoacidsbecause these are not common intermediates of the other pathways. Still, we willbe able to trace the carbon skeletons of all of these back to an -ketoacid.I make this point not because of any profound implications inherent in it, butrather as a way to simplify the learning of synthetic pathways of thenonessential amino acids.
The branch that leads towards tyrosine and phenylalanine has another branchpoint at prephenate. The only difference between the 2 resulting amino acids isthat the para carbon of the benzene ring of tyrosine is hydroxylated. Indeed, inmammals, phenylalanine is directly hydroxylated to tyrosine, catalyzed by theenzyme phenylalanine hydroxylase.
We will look at this pathway in a bit more detail, because it involves themolecule 5-phosphoribosyl--pyrophosphate (which wewill refer to as "PRPP" from now on). PRPP is also involved in thesynthesis of purines and pyrimidines, as we will soon see. In the first step ofhistidine synthesis, PRPP condenses with ATP to form a purine, N1-5'-phosphoribosylATP, in a reaction that is driven by the subsequent hydrolysis of thepyrophosphate that condenses out. Glutamine again plays a role as an amino groupdonor, this time resulting in the formation of 5-aminoamidazole-4-carboximideribonucleotide (ACAIR), which is an intermediate in purine biosynthesis.