JS-peptides

Fig. 2.15 Formulae and CD spectra in aqueous solution of jS-peptides with decreasing proportions ofACHC residues from two (83) to zero (85) [175]...

Fig. 2.18 The 12/10-helical structure of mixed jS-peptides as determined by NMR measurements in pyridine-c/5. (A) Stereo-view along the helix axis of the right-handed 12/10-helix of jS /jS -peptide 72 obtained by unrestrained...

Fig. 2.25 Conformational preferences and eight-membered turn motif of jS -peptides with 1 -aminomethylcyclopropanecarboxylic acid residues. X-ray crystal structures of dimer no, trimer m and tetramer 112 together with a model constructed using...

Fig. 2.30 Comparison of antiparallel hairpin structures in / -peptides 120-122. (A) / -Pep-tides 120, 121 with a 12-membered R/S dini-pecotic (Nip or/ -HPro) turn segment (gray color). Summary of backbone-backbone and side-chain-side-chain NOEs collected in CD2CI2 and X-ray crystal structure of 121 (stereo-view) [154, 193], The intramolecular H-bond N" 0 distances are shown. The angles (N-H -O) are 170.8° (inner H-bond) and 1 72.3 ° (outer H-bond). (B) jS-Peptide 122 with...

Fig. 21) was 94% as determined by HPLC [62]. Under these conditions, jS -peptides of up to 15 amino acids have been synthesized. In some cases, incomplete Fmoc deprotection in the last steps of the synthesis was observed when using 20% piperidine in DMF. The use of 1,8-diazabicy-clo[5.4.0]undec-7-ene resulted in significant improvements. Alternatively, )8-... 

Microwave SPPS is enabling technology currently involved in much active research. As new hardware is installed throughout the world, use and knowledge of microwave SPPS is increasing daily. For example, microwave energy was recently used to substantially increase the purity of several long jS-peptides, which suffer from low synthetic efficiency when conventional techniques are used [60]. 

The last comprehensive review of the chemistry of oxazolones covered the literature through 1954. Most of the studies up to that time stemmed from either interest in the role of azlactones as precursors of a-amino acids and peptides or the monumental studies on penicillin, which, for a time, was thought to possess an oxazolone ring, rather than the correct jS-lactam moiety. 

Many peptide antibiotics have novel structural motifs, such as cyclic structures and are often further modified, (such as in jS-lactamic antibiotics) and conjugated with sugars, lipids, and other molecules. 

Fig. 2.8 jS -amino acids synthesized for incorporation into j8-peptides [55, 97-99, 104, 134]... 

Fig. 2.40 Sequences and helical wheel representation of amphiphilic 2.5,2-helical jS-pep-tide 17-mers evaluated for antimicrobial activity [234, 248]. These peptides are exclusively composed of hydrophobic trans-ACPC...

C(jS) bond very similar to that which is observed for helical fi- and y-peptides and (ii) two types of intramolecular H-bonds involving a given C=0, namely C=0,--. - -N, +2 snd C=0,---H-N +3 which close the 12- and 14-membered H-bonded rings, respectively. 

The opioid receptors are for the endogenous opioids, peptide transmitters, jS-endorphin, endomorphins, enkephalins, dynorphins and nociceptin. Thus all the problems of drugs based on peptides need to be overcome in order for the roles of these... 

The ai polypeptide contains the receptors for the Ca " channel effectors as it can be photolabelled by DHPs and PAAs [30,39-41,56,57,63] and various other Ca channel effectors. The other subunits do not appear to be required for proper binding of Ca channel effectors [64], although there is some evidence from biochemical studies that the other subunits may modulate binding [65]. The oti and y subunits are very hydrophobic, while the a.2jd and jS subunits are very hydrophilic [57]. The a [30], 2, 6 and y [57] peptides are glycosylated, but oc is much less so than 2 [30]. The of both a peptides varies slightly on different types of SDS gels... 

A prime example of a Refolding model is that of the insulin protofilament (Jimenez et al., 2002). Insulin is a polypeptide hormone composed of two peptide chains of mainly o -helical secondary structure (Fig. 3A Adams et al., 1969). Its chains (21- and 30-amino acids long) are held together by 3 disulfide bonds, 2 interchain and 1 intrachain (Sanger, 1959). These bonds remain intact in the insulin amyloid fibrils of patients with injection amyloidosis (Dische et al., 1988). Fourier transform infrared (FTIR) and circular dichroic (CD) spectroscopy indicate that a conversion to jS-structure accompanies insulin fibril formation (Bouchard et al., 2000). The fibrils also give a cross-jS diffraction pattern (Burke and Rougvie, 1972). 

Hong JS, Hudson PM, Yoshikawa K, et al. 1985. Effect of chlordecone administration on brain and pituitary peptide systems. Neurotoxicology 6 167-182. 

JS Davies, RJ Thomas, MK Williams. Nuclear magnetic resonance spectra of ben-zoyldipeptide esters. A convenient test for racemisation in peptide synthesis. J Chem Soc Chem Commun 76, 1975. 

JS Davies, AK Mohammed. Assessment of racemisation in A-alkylated amino-acid derivatives during peptide coupling in a model dipeptide system. J Chem Soc Perkin Trans 1 2982, 1981. 

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