Free amino adds

From this first synthesis of an enzyme, two general conclusions were drawn. Firstly, it is possible to begin with free amino adds and to assemble them in the laboratory to give a real protein that possesses true enzymatic activity secondly, a new and independent kind of evidence was provided for the view that the primary structure of a protein determines its tertiary structure. 

Kosikowski, F. V. (1951). Paper chromatography of the free amino adds in American Cheddar cheese. ]. Dairy Sci. 34, 228-234. 

Note that the p/C, of a residue at the active site can vary substantially from the value observed for the free amino add in water [27]. For example, the active site of the enzyme acetoacetate decarboxylase features a lysine residue with a very low p/C, of 5.9 (cf. pJCa 9 for the free amino add). In this case, the pICa is influenced by an adjacent protonated lysine residue (Figure 5.6) [28,29]. A similar redudion, though less dramatic, is observed for aliphatic diamines (e.g., the two p/C, values for 1,4-diaminobutane are 10.80 and 9.35, respectively). 

Gunnarson G, Jakobsson AK, Hamberger A, SjOstrand J (1987) Free amino adds in the pre-retinal vitreous space. Effect of high potassium and nipecotic add. Exp Eye Res 44 235-244. 

Elemental High proportion of free amino adds Patients who require low fat... 

The analysis is carried out by incubatii the polypeptide with car boxyp otidase and watching ibr the appearance the Hrst free amino add that appears in acdution. fSome further degradation also occurs, since new C-terminus is produced when the first amino acid is cleaved off.)... 

Different transport systems are used for the uptake of free amino adds and peptides. In the case of the four amino add transport systems, transport of the amino acid is coupled with transport of an atom of sodium, that is, entry of the amino acid into a cell requires the co-transport of sodium. The four sodium-dependent amino acid transport systems are those spedfic for ... 

From the methods by which the polypeptides are obtained by synthesis it can only be concluded that their constituent amino acids are combined tc ether in the form of acid amides this method of combination also occurs in the case of the oxyaraino acids, e.g.., leucyl-isoserine, where the ester method of combination was excluded by special investigations. The question of their structure, however, still remains very complex, if the controversy concerning the structure of the amides and amino acids, which has not yet been settled, be taken into account. There is the possibility of lactam and lactim forms and of the free amino add and intramolecular salt these are illustrated by the four formulae for glycyl-glycine —... 

Wretlind A (1947) Free amino adds in dialyzed casein digest. Acta Physiol Scand 13 45-54 Yamakawa S (1920) Nippon Naika Gakkai Zasshi 17 122-126 Ziegler HK (1978) Sektionsbefund bei Dextranzwischenfall. Med Klin 73 1089-1090 Zozaya J (1932) Immunological reactions between dextran polysaccharides and some bacterial antisera. J Exp Med 55 353-360... 

The avian egg yolk does contain free amino acids (Williams et dl., 1954 Ducay et al., 1960 Fitzsimmons and Waibel, 1968) as well as proteolytic enzymes (Lineweaver et al., 1948 Emanuelsson, 1955 Ito, 1957) capable of replenishing the pool of free amino acids by degrading yolk proteins. Insofar as radioactively labeled amino acids injected into yolk are readily incorporated into embryo proteins, it is difiScult to exclude the possibility that the free amino adds in yolk are utilized by the embryo. However, the presence of amino adds and proteolytic enzymes does not necessarily indicate that free amino acids are quantitatively significant contributors to embryo growth or that they are essential nutrients-... 

Hermanussen M, Gonder U, Jakobs C, Stegemann D, Hoffmann G. Patterns of free amino adds in German convenience food products Marked mismatch between label information and composition. Eur J Clin Nutr. 2010 64 88-98. 

HPLC systems suitable for routine separation of dissolved free amino adds should have the following characteristics ... 

If free amino adds are to be analyzed in foods or aitimal feeds, it is advisable to remove matrix components such as hpids, carbohydrates, and nucleic adds from the sample. Of course, the necessary extraction steps are time-consuming, but higher concentrations of such compounds may interfere severely with the amino acid analysis. After hydrolysis of protein-free mixtures of nucleosides, nudeotides, and nucleic adds. Paddock et al. [48] even observed the formation of amino adds, predominantly glycine. 

To analyze free amino adds in plasma or tissue homogenates, it is necessary to remove proteins and peptides present in solution. The most widely used de-proteinization method is precipitation with 5-sulfosalicylic acid followed by centrifugation for separating the precipitate. In comparison to other predpitation agents such as trichloroacetic acid, perchloric add, picriiuc add, or acetoiutrile. 

In ligand-exchange chromatography (LEC), the separation of analytes is due to the exchange of ligands from the mobile phase with other ligands coordinated to metal ions immobilized on a stationary phase. LEC has been used successfully for the resolution of free amino adds, amino acid derivatives, and for enantiomeric resolution of racemic mixtures [3]. 

ScMeberle, R The role of free amino adds present in yeast as precursors of the odorants 2-acetyl-1-pytroline and 2-acetyltettahydropyridine in wheat bread crust. Z. Lebensm. Unters. Forsch. 191, 206 (1990)... 

In most foods, about 99% of amino adds are bound in proteins and peptides. The rest (about 1%) are free amino adds. There is a larger amount of free amino acids in foods in which proteolytic enzymes or chemical agents have hydrolysed proteins during manufacture or storage. Larger amounts of free amino acids can be found in some cheeses, beer and wine. The enzymatic hydrolysates of proteins (such as soy sauce) or addic protein hydrolysates (used as soup condiments) contain only free amino acids with small amounts of peptides, but no protein. 

Free amino add concentrations diminish during flor aging, but the evolution of each amino acid varies, depending on the situation. After 7 years flor aging, the concentration of proline, the most abundant amino acid in no-type sherries, representing 70% of the initial amount of total amino... 

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