Aminoacid residue

The protein polymers are highly sterospecific, the aminoacid residues always adopting the L-configuration, i.e. the same configuration as the reference substance L-malic acid. 

The structure of P pantotrophus (fomerly Thiospharea pantotropha, (3)) cytochrome cdi, the first of this type to have its crystal structure solved (4), shows that the enz5une is a homodimer of 567 aminoacid residues and each subunit contains both a c-type cytochrome center and a di heme center (Fig. 3). The di heme (Fig. 1) is unique to this class of enzyme and on that basis alone might be expected to be the catalytic site. The c-type cytochrome centers, which are defined by the covalent attachment of the heme to the polypeptide are usually, but... 

Cyclic peptides in which the ring consists solely of aminoacid residues with eupeptide links may be called homodetic cyclic peptides. Three representations are possible. Gramicidin S is given as an example. In this decapeptide, all amino acids are l, with the exception of Phe which is d, as is shown by o-Phe or oPhe. 

Another type of self-assembling channel transporting sodium and potassium through lipid membrane represent nanotubes built of eight D andL aminoacids residues discussed in Section 4.2.4 (Figure 4.13) [33],... 

An artificial intelligence search method was used in Ref. [330] to select a subset of 15-20 aminoacid residues among ca. 150 such residues as being most relevant for electron transfer. 

Pederson and co-workers (see Ref. 25) have isolated a peptide of Mr 2200, from ACTH-stimulated rat adrenals, which contained 15% of basic aminoacid residues. The polar side-chain groups were thought to alter membrane structure so that transference of cholesterol towards the cyt P-450scc on the inner membrane would be favoured. 

Hen egg lysozyme is a small enzyme, having a single polypeptide chain of 129 aminoacid residues and a molecular mass of approximately 14400 Da, that catalyzes the hydrolysis of glycosidic linkages in bacterial cell walls. The schematic illustration of the active sites of lysozyme is shown in Fig. 10.29. 

Independent from studies oriented towards the search for better anti-AIDS drugs, compounds of general formula 60 and 61, where R are natural aminoacid residues, were reacted with simple alcohols like methanol. In this way we prepared, with high purity and satisfactory yields, otherwise difficult to obtain phos-phorothioate [87] and phosphorodithioate [88] amidoesters 64 considered as the analogues of transition state for the cleavage of peptide bond by proteases [89]. 

Similar results have by now been obtained for practically all the aminoacid residues of proteins and they all lead to similar individual conclusions. 

For study of the role of phosphate groups for many enzymes the phosphamide derivatives with phosphorilic activity are using. Such N-methylimidazole derivatives have increased the reactability in relation to a number of nucleophiles, especially to amine, in which role they cannot act as functional aminoacid residuals of the active center of an enzyme or the site of the flavin bindings. ... 

The most important and universal type of chemical equilibria to which a heme protein is subjected in natural environments is pH equilibria, involving the protein aminoacid residues and the ionizable groups of the porphyrin, the propionate side chains. Beside the effects on the overall protein structure, which are outside the scope of this review, the major consequences of proton equilibria may be the changes of the heme reduction potential (electron affinity), called the redox-Bohr effect (see Sect. 3.2), by analogy to the pH effect on the oxygen affinity of hemoglobin (Bohr effect). 

A new cyclic heptapeptide cupolamide A (55) was isolated from two samples of the sponge Theonella cupola collected in Indonesia and Okinawa [49]. Three of the aminoacid residues, fram,-4-hydroxyproline, homoarginine and 2,4-diaminobutanoic acid are of uncommon occurrence in particular the hydroxy-proline is a constituent of collagen and occasionally has been found in terrestrial biota [50] and in marine... 

Callipeltins A-C are a new class of cyclic depsipeptides isolated from Callipelta sp. [137,138], Callipeltin A (125) appears very intriguing because of some structural features such as the presence of four new aminoacid residues, not previously isolated from natural sources (P-MeO-Tyr, N-Me-Gln, di-Me-Glu and 4-amino-7-guanidino-2,3-dihydroxy-eptanoic acid), the N-terminus blocked with a 3-hydroxy acid residue and... 

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