Peptide results

A typical TIC chromatogram from an analysis of peptides resulting from enzymatic digest of myoglobin. The peaks represent individual peptides eluting from an LC column and being mass measured by a spectrometer coupled to it through a dynamic-FAB inlet/ion source. 

The gastrointestinal hormone secretin is prepared by fragment condensation. The tetrapeptide L-Thr-L-Phe-L-Thr-L Ser is coupled to the C-terminal nonadecapeptide of the hormone, and the tetrapeptide L-His-L-Ser- 3-benzyl-L-Asp-Gly is coupled to the tricosa-peptide resulting from the first coupling. 

Figure 5. Partial peptidic sequences of peptides resulting fi-om tryptic cleavage PME isoforms.

Because of this length dependence, IR and VCD of -turns may provide a means of discriminating and detecting them in a protein structure. Short Aib peptide results provide examples of type III /3-turn VCD (Yasui et al., 1986b), while cyclic peptides have been used to study type I and II turns, which are implied to have unique VCD band shapes (Wyssbrod and Diem, 1992 Xie et al., 1995). We have identified distinct turn modes... 

The above peptide results established general patterns that are apparent in protein spectra. However, most proteins differ from small peptides in terms of the degree of solvation and the uniformity of secondary structure segments. Although a peptide helix may terminate in a large... 

Nesiritide is manufactured using recombinant techniques and is identical to the endogenous B-type natriuretic peptide secreted by the ventricular myocardium in response to volume overload. Consequently, nesiritide mimics the vasodilatory and natriuretic actions of the endogenous peptide, resulting in venous and arterial vasodilation increases in cardiac output natriuresis and diuresis and decreased cardiac filling pressures, sympathetic nervous system activity, and renin-angiotensin-aldosterone system activity. 

A completely different tactic is the use of microwave energy absorption of this energy by a peptide results in decreased aggregation. Lithium salts facilitate the solution of peptides in these polar solvents, increase the rate of swelling of polar resins, and improve coupling yields. Sometimes the order of addition of two solvents to a peptide makes a difference. The inclusion of pyridine can also have a beneficial... 

Figure 10.13 The reaction of FDNB with compounds containing a free amino group. The reaction at pH 9.5 between FDNB and amino acids or peptides results in the formation of yellow-coloured dinitrophenyl derivatives.

The characteristic properties of peptides result from the presence of a chain of several or many amide bonds. A first problem is that of numbering, and here Fig. 6.1 taken from the IUPAC-IUB rules may help. A second and major aspect of the structure of peptides is their conformational behavior. Three torsion angles exist in the backbone (Fig. 6.2). The dihedral angle co (omega) describes rotation about C-N,

rotation about N-C , and ip (psi) describes rotation about C -C. Fig. 6.2 represents a peptide in a fully extended conformation where these angles have a value of 180°. 

We have chosen animal cell cultures for that purpose, bearing in mind the following advantages of such system (i) the action of peptide results in a limited number of integral responses, when a variety of biochemical mechanisms gives rise to uniform effects, such as cell death or stimulation/inhibition of cell proliferation rate (ii) the test requires low, picomolar amounts of peptides (iii) the results are treated by simple and reliable statistic methods. 

As many of the phenotypic changes induced following PhoPQ activation involve host defense peptide resistance characteristics, it is postulated that host defense peptides serve as an endogenous ligand for PhoQ Indeed, the exposure of S. typhimurium to sublethal concentrations of cationic antimicrobial peptides results in activation of the PhoPI regulon and host defense peptide resistance phenotypes. " Supporting... 

The introduction at the C- or N-terminal position of a crown ether unit has been used as a strategy to control the aggregation of poly(benzyl glutamate) derivatives 19 The incorporation of the crown unit at the C-terminal position is performed using (benzo-15-crown-5)-4-amine as initiator of the polymerization of l-G1u(OBz1)-NCA. Physical properties of such crown derivatives can be modulated by the formation of sandwich 2 1 complexes driven by the addition of specific alkali metal ions. In the reported case, the formation of K+ sandwich complex between two C-terminal benzo-15-crown-5 modified helical polypeptides induced aggregation. In a similar approach,f20 addition of Cs+ to 18-crown-6 terminated helical peptides results in the formation of supramolecular assemblies having membrane ion conductivity activities. 

However, the high molecular weight poly-peptides resulting from initiation by sodium methoxide did not show unusually broad distribution (unpublished results of Blout und Doty). 

Peptides resulting from cleavage of the intact protein are generally separated by column chromatography. The isolated peptides may then be analyzed (step 5) to determine both their amino acid composition and their sequence. Se-... 

---