摘要:

AbstractThe Y362K mutation in the neck domain of conventional kinesin fromNeurospora crassaprovokes a significant reduction of the rate of movement along microtubules. Since the α‐helical coiled‐coil structure of the neck region is implicated in the mechanism of the processive movement of kinesins, a series of peptides related to the heptad region 338–379 of the wild‐type and the variant fungal kinesins were synthesized as monomers and asN‐terminal disulfide dimers, crosslinked to favour self‐association into coiled‐coil structures entropically. A comparison of the dichroic properties of the peptides and the effects of trifluoroethanol and peptide concentration clearly confirmed the strong implication of the single point mutation in destabilizing the intrinsic propensity of the peptides to fold into the supercoiled conformation. That there is a correlation between the stability of the coiled‐coil and rate of movement of the kinesin is confirmed. Copyright © 2003 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/psc.443

出版商:John Wiley&Sons, Ltd.    

年代:2003

数据来源: WILEY

摘要:

AbstractPathogenic prion proteins (PrPSc) are thought to be produced by α‐helical to β‐sheet conformational changes in the normal cellular prion proteins (PrPC) located solely in the caveolar compartments. In order to inquire into the possible conformational changes due to the influences of hydrophobic environments within caveolae, the secondary structures of prion protein peptides were studied in various kinds of detergents by CD spectra. The peptides studied were PrP(129–154) and PrP(192–213); the former is supposed to assume β‐sheets and the latter α‐helices, in PrPSc. The secondary structure analyses for the CD spectra revealed that in buffer solutions, both PrP(129–154) and PrP(192–213) mainly adopted random‐coils (∼60%), followed by β‐sheets (30%–40%). PrP(129–154) showed no changes in the secondary structures even in various kinds of detergents such as octyl‐β‐D‐glucopyranoside (OG), octy‐β‐D‐maltopyranoside (OM), sodium dodecyl sulfate (SDS), Zwittergent 3–14 (ZW) and dodecylphosphocholine (DPC). In contrast, PrP(192–213) changed its secondary structure depending on the concentration of the detergents. SDS, ZW, OG and OM increased the α‐helical content, and decreased the β‐sheet and random‐coil contents. DPC also increased the α‐helical content, but to a lesser extent than did SDS, ZW, OG or OM. These results indicate that PrP(129–154) has a propensity to adopt predominantly β‐sheets. On the other hand, PrP(192–213) has a rather fickle propensity and varies its secondary structure depending on the environmental conditions. It is considered that the hydrophobic environments provided by these detergents may mimic those provided by gangliosides in caveolae, the head groups of which consist of oligosaccharide chains containing sialic acids. It is concluded that PrPCcould be converted into a nascent PrPSchaving a transient PrPSclike structure under the hydrophobic environments produced by gangliosides.

ISSN:1075-2617    

DOI:10.1002/psc.447

出版商:John Wiley&Sons, Ltd.    

年代:2003

数据来源: WILEY

摘要:

AbstractThe process of native chemical ligation (NCL) is well described in the literature. AnN‐terminal cysteine‐containing peptide reacts with aC‐terminal thioester‐containing peptide to yield a native amide bond after transesterification and acyl transfer. AnN‐terminal cysteine is required as both theN‐terminal amino function and the sidechain thiol participate in the ligation reaction. In certain circumstances it is desirable, or even imperative, that theN‐terminal region of a peptidic reaction partner remain unmodified, for instance for the retention of biological activity after ligation. This work discusses the synthesis of a pseudo‐N‐terminal cysteine building block for incorporation into peptides using standard methods of solid phase synthesis. Upon deprotection, this building block affords ade factoN‐terminal cysteine positioned on an amino acid sidechain, which is capable of undergoing native chemical ligation with a thioester. The syntheses of several peptides and structures containing this motif are detailed, their reactions discussed, and further applications of this technology proposed. Copyright © 2003 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.448

出版商:John Wiley&Sons, Ltd.    

年代:2003

数据来源: WILEY

摘要:

AbstractThe angiotensin II AT1Areceptor belongs to the G‐protein coupled receptors (GPCRs). Like other membrane proteins, GPCRs are not easily amenable to direct structure determination by the currently available methods. The peptide encompassing the putative first extracellular loop of AT1A(residues Thr88‐Leu100, el1) has been synthesized along with a cyclic model where the linear peptide has been covalently linked to a template designed to keep the distance between the peptide termini as expected in the receptor. The conformational features of the two molecules have been studied using circular dichroism and NMR techniques. The region W94PFG97forms a type‐II β‐turn and undergoes a Trp‐Pro peptide bondcis‐transisomerization in both peptides confirming that these characteristics are intrinsic to el1. In addition, the presence of the spacer seems to modulate the flexibility of the peptide. Copyright © 2003 European Peptide Society and John Wi

ISSN:1075-2617    

DOI:10.1002/psc.449

出版商:John Wiley&Sons, Ltd.    

年代:2003

数据来源: WILEY

摘要:

AbstractHeparin‐binding EGF‐like growth factor (HB‐EGF), which belongs to the EGF‐family of growth factors, was isolated from the conditioned medium of macrophage‐like cells. To investigate the effect ofN‐ andC‐terminal residues of the EGF‐like domain of HB‐EGF in the binding affinity to the EGF receptor on A431 cell. We synthesized HB‐EGF(44–86) corresponding to the EGF‐like domain of HB‐EGF and itsN‐ orC‐terminal truncated peptides. Thermolytic digestion demonstrated three disulfide bond pairings of the EGF‐like domain in HB‐EGF is consistent with that of human‐EGF and human‐TGF‐α. HB‐EGF(44–86) showed high binding affinity to EGF‐receptor, like human‐EGF. The truncation of theC‐terminal Leu86residue from HB‐EGF(44–86), HB‐EGF(45–86) or HB‐EGF(46–86) caused a drastic reduction in the binding affinity to the EGF receptor. These results suggest that the EGF‐like domain of HB‐EGF plays an important role in the binding to the EGF receptor, and itsC‐terminal Leu86residue is necessary for binding with the EGF‐receptor. In addition, the deletion of the twoN‐terminal residues (Asp44‐Pro45) from HB‐EGF(44–86) caused a 10‐fold decrease in relative binding affinity to the EGF receptor. This indicates that the twoN‐terminal residues of the EGF‐like domain of HB‐EGF are necessary for its optimal binding affinity t

ISSN:1075-2617    

DOI:10.1002/psc.450

出版商:John Wiley&Sons, Ltd.    

年代:2003

数据来源: WILEY