摘要:

AbstractSiderophores are low molecular weight iron chelators, produced by virtually all bacteria, fungi and some plants. They serve to deliver the essential element iron, barely soluble under aerobic conditions, into microbial cells. Siderophores are therefore important secondary metabolites which are very often based on amino acids and their derivatives. Biosynthesis, transport, regulation and chemical synthesis of natural siderophores and their analogues is of considerable interest for the protein and peptide chemist. This review gives an overview of the structural classes of peptidic siderophores, along with data on their biosynthesis. On a number of representative examples, strategies and schemes of their chemical synthesis are described. ©1998 European Peptide Society and John Wiley&Sons, Ltd

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199805)4:3<147::AID-PSC136>3.0.CO;2-C

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractMolecules encoded by the major histocompatibility complex (MHC) are polymorphic integral membrane proteins adapted to the presentation of peptide fragments of foreign antigens to antigen‐specific T‐cells. The diversity of infectious agents to which an immune response must be mounted poses a unique problem for receptor–ligand interactions; how can proteins whose polymorphism is necessarily limited bind an array of peptides almost infinite in its complexity? Both MHC class I and class II determinants have achieved this goal by harnessing a limited number of peptide side chains to anchor the epitope in place while exploiting conserved features of peptide structure, independent of their primary sequence. While class I molecules interact predominantly with the N‐ and C‐termini of peptides, class II determinants form an extensive hydrogen bonding network along the length of the peptide backbone. Such a strategy ensures high‐affinity binding, while selectively exposing the unique features of each ligand for recognition by the T‐cell receptor. © 1998 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199805)4:3<182::AID-PSC144>3.0.CO;2-S

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractPermeable resins cross‐linked with long PEG chains were synthesized for use in solid‐phase enzyme library assays. High molecular weight bis‐amino‐polyethylene glycol (PEG) 4000, 6000, 8000 were synthesized by a three‐step reaction starting from PEG‐bis‐OH. Macromonomers were synthesized by partial or di‐acryloylation of bis‐amino‐PEG derivatives. Bis/mono‐acrylamido–PEG were copolymerized along with acrylamide by inverse suspension copolymerization to yield a less cross‐linked resin (TypeI,compounds6–9). Furthermore, acryloyl–sarcosin ethyl ester was co‐polymerized along with bis‐acrylamido PEG to obtain more crosslinked capacity resin (TypeII,compounds13–19).N,N‐Dimethylacrylamide was used as a co‐monomer in some cases. The polymer was usually obtained in a well‐defined beaded form and was easy to handle under both wet and dry conditions. The supports showed good mechanical properties and were characterized by studying the swelling properties, size distribution of beads, and by estimating the amino group capacity. Depending on the PEG chain length, the monomer composition and the degree of cross‐linking the PEGA supports showed a high degree of swelling in a broad range of solvents, including water, dichloromethane, DMF, acetonitril, THF and toluene; no swelling was observed in diethyl ether. The PEGA resins (TypeI) with an amino acid group capacity between 0.07 and 1.0 mmol/g could be obtained by variation of the monomer composition in the polymerization mixture. Fluorescent quenched peptide libraries were synthesized on the new polymer using a multiple column library synthesizer and incubated with the matrix metalloproteinase MMP‐9 after it had been activated by 4‐aminophenyl mercuric acetate resulting in 67/83 kDa active enzyme. The bright beads were separated manually under a fluorescence microscope and sequenced to obtain peptide substrates for MMP‐9. After treatment with ethylene diamine, high‐loaded resins (TypeII) have been employed in continuous flow peptide synthesis to yield peptides in excellent yield and purity. © 19

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199805)4:3<195::AID-PSC141>3.0.CO;2-R

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractFractionation of bovine brain extracts followed by automatic Edman sequencing of individual components resulted in identification of 107 endogenous peptides formed from functional proteins (haemoglobin, myelin basic protein, cytochromecoxidase, etc) or unknown precursors. Several of the newly identified brain peptides demonstrate different types of biological activity; some of the substances show considerable overlap with the known biologically active peptides. It is suggested that these peptides should participate in regulation of extracellular and intracellular biochemical processes. A concept of ‘tissue‒specific peptide pool’ is formulated describing a novel system of peptidergic regulation, complementary to the conventional hormonal and neuromodulatory systems. According to that description functional proteins provide their proteolytically derived fragments for maintaining the tissue homeostasis by modulating the availability of peptide receptors to respective ‘true’ ligands. © 1998 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199805)4:3<211::AID-PSC138>3.0.CO;2-O

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY