molecular aspects of milk protein biosynthesis; ..
The distinctive cyclic structure of proline's side chain locks its φ backbone dihedral angle at approximately -75°, giving proline an exceptional conformational rigidity compared to other amino acids. Hence, proline loses less conformational entropy upon folding, which may account for its higher prevalence in the proteins of thermophilic organisms. Proline acts as a structural disruptor in the middle of regular secondary structure elements such as alpha helices and beta sheets; however, proline is commonly found as the first residue of an alpha helix and also in the edge strands of beta sheets. Proline is also commonly found in turns, which may account for the curious fact that proline is usually solvent-exposed, despite having a completely aliphatic side chain. Because proline lacks a hydrogen on the amide group, it cannot act as a hydrogen bond donor, only as a hydrogen bond acceptor.
Biosynthesis of the Milk Proteins
According to popular belief, eating tryptophan in turkey meat causes drowsiness. Turkey does contain tryptophan, which does have a documented sleep-inducing effect as it is readily converted into serotonin by the body. However, ingestion of turkey alone has not been proven to have this effect. An additional hypothetical mechanism is as follows: A large quantity of any food,[original research?] such as a Thanksgiving feast, introduces large quantities of both carbohydrates and branched-chain amino acids releasing insulin. Insulin stimulates the uptake of large neutral branched-chain amino acids (and not tryptophan) by muscle cells through the myocyte membranes. The result is an increase in the ratio of tryptophan to large neutral amino acids in the blood. This reduces competition with other amino acids for the Large Neutral Amino Acid Transporter protein for uptake of tryptophan across the blood-brain barrier into the central nervous system. Once inside the central nervous system, tryptophan is converted into serotonin by the raphe nuclei, and serotonin is further metabolised into melatonin by the pineal gland.
Alcoholic beverage consumption at holiday feasts is likely to compound the effect.[original research?]
Cycloretinal is a non-degradable, toxic byproduct of the visual cycle. Photochemical activation of the metabolite leads to oxidative damage of the retinal pigment epithelium and adjacent photoreceptor cells. Biochemical evidence from our lab has recently revealed that beta-lactoglobulin (BLG), the principal whey protein in milk, biosynthesizes the lipofuscin cycloretinal (all-trans retinal dimer). The protein survives the pasteurization process, is acid stable and a large fraction of the protein is transported intact through the blood stream (as supported by rabbit studies). Proteomic studies performed by Crabb and co-workers have shown that the protein is present in drusen.
Calories in breast milk: Nutritional information
Biosynthesis of fatty acids is strictly regulated. The primary determination of lipogenesis or lipolysis is the equilibrium between monomeric and polymeric acetyl-CoA carboxylase. Several hormones, including insulin, glucagon, glucocorticoids, epinephrine, the secondary messenger cAMP, as well as diet composition and nutrient manipulation all exert important regulatory action on lipid metabolism. However, the recent discovery that genetics play an integral part in determining the extent of fatty acid synthesis may prove to be the most beneficial breakthrough in the "War on Fat". Future investigations and studies of leptin and its method of transduction may unveil the mystery of fat synthesis and allow the development of pharmacological agents to prevent obesity.
Growth and exopolysaccharide production by …
Aspartic acid is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CO2H. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its three letter code is asp, its one letter code is D, and its codons are GAU and GAC. It is classified as an acidic amino acid, together with glutamic acid. Aspartic acid is pervasive in biosynthesis.
Protein-Rich Foods and Vegan Protein Alternatives
The pathways linking arginine, glutamine, and proline are bidirectional. Thus, the net utilization or production of these amino acids is highly dependent on cell type and developmental stage.
Keyword - Protein biosynthesis (KW-0648)
Aspartic acid is non-essential in mammals, being produced from oxaloacetate by transamination. In plants and microorganisms, aspartic acid is the precursor to several amino acids, including four that are essential: methionine, threonine, isoleucine, and lysine. The conversion of aspartic acid to these other amino acids begins with reduction of aspartic acid to its "semialdehyde," HO2CCH(NH2)CH2CHO. Asparagine is derived from aspartic acid via transamidation: