Penultimate residue

With the C-terminal residue introduced as part of the BAL anchor and the penultimate residue incorporated successfully by the optimized acylation conditions just described, further stepwise chain elongation by addition of Fmoc-amino acids generally proceeded normally by any of a variety of peptide synthesis protocols. 

CONSTITUTIONAL FACTORS THAT DEFINE THE EXTENT OF STEREOMUTATION DURING COUPLING THE N-SUBSTITUENT OF THE ACTIVATED RESIDUE OR THE PENULTIMATE RESIDUE... 

FIGURE 5.19 Approaches for synthesis of protected peptides using acid-sensitive protectors. For (A) the last residue is incorporated as the Cbz-derivative. (B) The chain is assembled on a substituted oxime resin,44 starting at the penultimate residue. The chain is then detached from the resin by displacement by the carboxy-terminal residue of the target peptide, which may be a free (terf-butylammonium salt) or carboxy-substituted residue. (C) An alternative for producing acids by use of the oxime resin is transesterfication of the peptide with A-hydroxypiperidine, followed by reduction to remove the piperidino substituent. 

FIGURE 7.33 Enantiomerization (A) of the terminal residue and (B) of the penultimate residue of an activated peptide by tautomerization of the 5(4//)-oxazolone of the terminal residue. [Bergmann and Zervas, 1928],... 

ENANTIOMERIZATION OF THE PENULTIMATE RESIDUE DURING COUPLING OF AN N -PROTECTED PEPTIDE... 

The COOH-terminal residue, determined both with carboxypeptidases A and B (43), was lysine (5.4 moles/mole of enzyme), and the penultimate residue was alanine. Additional components were not detected in either digestion (34). 

The steps involved in this synthetic sequence (Fig. 2) are described in Subheadings 3.2.1.-3.2.5. These include (1) reductive amination involving BAL-resin and the penultimate residue of the peptide target, with its carboxyl group... 

This is done as described in Subheading 3,1,1, but using the eventual penultimate residue of the peptide target with its carboxyl group protected as an allyl or ferf-butyl ester. 

The proline-specific aminopeptidase P(AMPP) specifically hydrolyzes the N-terminal amino acid from peptides in which the penultimate residue is a proline. It was earlier shown that AMPP from E. coli was activated by both Mn and Co +, and EPR and EXAFS spectra of the Mn +-reconstituted enzyme were consistent with the presence of a dinuclear center. Subse-... 

Asn and His are the respective C-tenninal and penultimate residues of the intein. Cys, Ser and Thr are the residues immediately C-terminal to each of the two splice junctions (i.e. N-terminal residues of intein and C-extein). The information concerning intein sequences, properties and references are available onhne at InBase (http //www.neb.com/ neb/inteins.html. The proposed sphcing mechanisms are shown in Figure 13.19. 

The result of a site-specific mutagenesis experiment suggested that the carboxyl residue of aspartate 121, which is the penultimate residue in the H1-H2 junction, is involved in the binding interaction between the enzyme and ouabain [121], The authors considered the possibilities that the carboxylate may be interacting with another extracellular region of NaVK -ATPase in a manner which helps to maintain the integrity of the binding site or, alternatively, may directly interact with the ouabain molecule, perhaps with its lactone moiety. 

A -diisopropylcarbodiimide (DIPCDI) as coupling agents. Key aspects of on-resin NCL include Fmoc/tBu chemistry, side-chain anchoring, allyl protection of the penultimate residue to allow introduction of the C-terminal thioester later in the synthetic sequence, anew derivative, Trt-Cys(Xan)-OH, which facilitates selective... 

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