Amino acids distribution

Small ACTH fragments related to ACTH-(4-10) have also been investigated for the presence of ordered structure. CD of ACTH--(5-10) in TFE showed a random structure (50) as was found with H-NMR for fragment 4-10 (51). The addition of anionic or cationic surfactants to an aqueous solution of ACTH-(4-11) dit not promote any a-helix or 3-form in this peptide (CD experiments S2). When ACTH-(1-14) and 1-10 were measured by CD and NMR respectively, indications for a helical or ordered structure were found (90, ). Thus it seems that the addition of the non-helix "prone" fragment 1-3 or 1-4 can promote the formation of a helical structure in the adjacent sequence. Arguments in favour of this come from the theoretical work of Argos and Palau (53) on amino acid distribution in protein secondary structures. They found that Ser and Thr frequently occur at the N-terminal helical position (cf. Ser in ACTH) to provide stability the position adjacent to the helical C-terminus is often occupied by Gly or Pro (adjacent toTrp in ACTH we have Gly ) acidic amino acid residues are frequently found at the helix N-terminus (cf. Glu in ACTH) and/or basic residues at the C-terminus (cf. Arg ). 

The photosynthetic block precedes sucrose synthesis, and sucrose partially reverses the inhibition caused by the lack of fixation of carbon dioxide. D-Fructose disappears first, after treatment, followed by sucrose, and then u-glucose.188 It is likely that other metabolic systems are involved as well, since the amino acid distributions were not identical to the I4C02 dark-fixation products.189 Uptake of sucrose-14C increased some acids (as-... 

To explain the species-specific amino acid pattern one can assume that each organism secretes one particular calcifying protein which to a limited extent is controlled by the environment. Alternately, a series of different proteins can yield the observed pattern, however, we have to postulate that each one is secreted at a constant rate. Changes in rate of secretion, perhaps environmentally induced, will effect the ratio of the individual proteins and thus account for slight variation in the amino acid distribution in the hydrolyzed matrix. 

Pawagi AB, Wang J, Silverman M, et al. Transmembrane aromatic amino acid distribution in P-glycoprotein. A functional role in broad substrate specificity. J Mol Biol 1994 235(2) 554-564. 

AMINO ACID DISTRIBUTION"1 IN AN ARABINOGALACTAN-PROTEIN FROM E. PURPUREA... 

Essential amino acid distribution in a casein hydrolysate suitable for parenteral injection. Am. J. Pharm., 116, 368 (1944). With D. Bolling. 

The close match of the amino acid distributions in meteorites and the Miller-Urey synthesis suggests that the meteoritic amino acids were produced by the essential steps of the Miller-Urey synthesis. It is not yet clear what these essential steps would be in a nebular setting. Synthesis of intermediates obviously does not require an electric discharge, but can also be achieved from CO, NHj, and H2. The required... 

The simple comparison of amino acid distributions in bacteria and phytoplankton reveals no obvious differences between these two possible autochthonous sources of dissolved proteins. Accordingly, the amino acid distribution in HMWDOM is similar to the distribution in phytoplankton, bacteria and sediment traps. The relationship between the amino acid distribution in total DOM and various particulate fractions is more variable. In general, it appears that amino acid distribution alone cannot identify the dominant source of dissolved proteins/peptides. However, assuming that the primary source of dissolved proteins in the ocean is bacteria and phytoplankton, these data support the interpretation that hydrolysable proteins in DOM and HMWDOM maintain a source-like amino acid distribution. 

In the Arctic and Antarctic Ocean amino acids were also found in humic substances isolated from DOM by XAD-2 resins (Hubberten et ai, 1995). The concentration of THAA in humic substances was between 233—246 nM, with aU hydrolysable amino acids in the deep ocean and 60% of amino acids in the surface ocean residing in this fraction. Glycine was by far the most abundant amino acid detected in the humic fraction. These authors concluded that amino acids in the XAD-2 extracts represent a refractory protein background that is present throughout the ocean. The dominance of this refractory protein background in the surface and deep ocean could explain the relatively stable amino acid distribution observed by Yamashita and Tanoue (2003) at their open ocean sites. 

Figure 3.46. "Inside Out" Amino Acid Distribution in Poiin. The outside of porin (which contacts hydrophobic groups in membranes) is covered largely with hydrophobic residues, whereas the center includes a water-filled channel lined with charged and polar amino acids.

Amino Acids. Kemp and Mudrochova (1973) determined amino acids and amino sugars by ion-exchange chromatography in 6N HCl hydrolysates of humic and fulvic acids from Lake Ontario sediments. They obtained total amino acids of 21.5% for humic acid and 12.6% for fulvic acid. Total amino sugars accounted for only 1.9 and 1.3% for humic acid and fulvic acid, respectively. They found the amino acid distribution in the humic acid resembled that of zooplankton and suspended sediment samples, with the exception of glycine which was higher in the sediments. This lends support for the assumed autochthonous nature of lake sediment organic matter. On the other hand, basic amino acid concentrations were low in the fulvic acid and its amino acid distribution resembled the combined form in the interstitial waters. 

In the seven lakes studied by Yamamoto (1983), amino acid distribution of fulvic acid, humic acid, and humin resembled each other. However, after detailed examination of amino acid distribution, the following regularities were found to exist in almost all humic substances studied ... 

These regularities hold for the amino acid distribution in humic acid and fulvic acid reported by Kemp and Mudrochova (1973). 

Figure 2.50 Inside out" amino acid distribution in porin. The outside of porin (which...

Butterworth RF, Merkel AD, Landreville F (1982) Regional amino acid distribution in relation to function in insulin hypoglycaemia. J Neurochem 3S 1483-1489. 

Wilson, I. B. H Gavel, Y., von Heijne, G. (1991). Amino acid distributions around O-linked glycosylation sites. Biochem. J. 275, 529-534. 

Sup35 is a 685 residue protein that can be divided into three regions based on amino acid distribution and homology to other proteins (Fig. 

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