Amino-acid analyser pattern

In recent years, a number of workers have published amino acid analyses of the sweet potato (38, 43, 35, 22, 18). The overall picture is that the sweet potato amino acid pattern is of good nutritional quality but that the variability of individual amino acids both within the same cultivar and across cultivars is very high. For example, Walter et al. (44) reported that with the exception of aromatic amino acids, every essential amino acid has a score of less than 100 in one or more cultivars. The amino acid score is defined as the g of amino acid in 100 g of test protein divided by the number of g of that amino acid in the FAO/WHO reference pattern times 100. Bradbury et al. (22) showed that, for the same cultivar, environmental effects on the amino acid patterns is significant. For three cultivars, they found a mean percent standard deviation for all amino acids of 24.2,... 

Cys(Acm)U5]-endothelin I [H-Cys(Acm)-Ser-Cys-Ser-Ser-Leu-Met-Asp-Lys-Glu-Cys-Val-Tyr-Phe-Cys(Acm)-His-Leu-Asp-Ile-Ile-Trp] (22 0.41 pmol) was treated with silver(I) trifluoroacetate/DMSO/ 1M HCI in an analogous manner to that described in Section 6.1.1.1, The HPLC elution pattern of the crude peptide showed two peaks, with retention times identical to those of endothelin-I and an isomer in a ratio of 8 1. Each product was purified by HPLC to yield endothelin-I (23) and its isomer (7.5% yield 62%) these products were characterized by HPLC, FAB-MS, and amino acid analyses. 

Studies of KH clearly indicate complexity that is only partially resolved (49). DiflFerential staining reveals small, dense, homogeneous particles within amorphous KH masses, usually associated with tono-fibrils (32, 48, 49). Amino acid analyses of supposed KH materials show at least three distinctive patterns (see Table I). The amorphous material of Tezuka and Freedberg (72) has much less proline and cystine than KH studied by Matoltsy (51). Other workers have associated histidine with KH in granular cells (48, 49, 76). Tezuka s histidine values (72) fall between those of Matoltsy (51) and Hoober (76) and conceivably represent an analysis of mixed components. UgeFs bovine material is a nucleoprotein that may be either a ribosomal product or still another KH component (71, 77). 

The next part of this chapter will include a discussion of the interpretation of amino acid patterns, with particular emphasis on plasma The rationale behind this discussion is that most amino acid analyses are undertaken in children with a view to diagnosing inborn errors of metabolism. One is then faced with the difficulty of interpreting a particular ammo acid pattern to decide whether or not this pattern is normal and, if it is abnormal, to... 

This Chapter focuses on analyses that can be performed based solely on the primary sequence of a protein. Several rationales can be applied. Physico-chemical characteristics of individual amino acids are one basis for predictions of gross structural features. For example, particular repetitive patterns may suggest a coiled-coil structure while in general secondary structure can be predicted based on an a statistical analysis of the primary sequence. The definition of signals recognized by the cellular transport machinery allow the prediction of subcellular location. Although somewhat unsystematic such observations can provide valuable hints as to the structure and/or function of a protein. 

After direct high-resolution structural measurements on proteins became practicable, interest in crystalline amino acids decreased, but became renewed in attempts to simulate the distribution of electronic charge density in biopolymers using amino acids and simple peptides as model systems, to derive some transferable parameters and potentials [2-15]. Another research direction involved these systems and their packing patterns to mimic selected folds and interaction patterns of biopolymers. Typical molecular conformations and patterns of hydrogen bonds and packing in the structures of crystalline amino acids have been reviewed [16-19]. Similar analyses were performed for small peptides [18, 20-22]. 

Secondary structure prediction methods have been complemented by packing analyses of amino acid residues in globular proteins. Packing arrangements have been examined extensively [13, 14] in attempts to identify preferred interaction patterns between non-contiguous amino acid residues. While there is no straightforward way to cast this information into a scheme for prediction of protein structure from sequence, it can certainly be used for plausibility checks on hypothetical protein models or to score protein models obtained by protein folding simulations on lattices [15]. 

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