Progress in the development of therapeutic antibodies targeting prion proteins and β-amyloid peptides

Prion diseases and Alzheimer’s disease (AD) are characterized by protein misfolding, and can lead to dementia. However, prion diseases are infectious and transmissible, while AD is not. The similarities and differences between these diseases have led researchers to perform comparative studies. In the last 2 decades, progress has been made in immunotherapy using anti-prion protein and anti-β-amyloid antibodies. In this study, we review new ideas and strategies for therapeutic antibodies targeting prion diseases and AD through conformation dependence.     

β-turn tendency in N-methylated peptides with dehydrophenylalanine residue: DFT study

The tendency to adopt β‐turn conformation by model dipeptides with α,β‐dehydrophenylalanine (ΔPhe) residue in the gas phase and in solution is investigated by theoretical methods. We pay special attention to a dependence of conformational properties on the side‐chain configuration of dehydro residue and the influence of N‐methylation on β‐turn stability. An extensive computational study of the conformational preferences of Z and E isomers of dipeptides Ac‐Gly‐(E/Z)‐ΔPhe‐NHMe ( 1a / 1b ) and Ac‐Gly‐(E/Z)‐ΔPhe‐NMe₂ ( 2a / 2b ) by B3LYP/6‐311++G(d,p) and MP2/6‐311++G(d,p) methods is reported. It is shown that, in agreement with experimental data, Ac‐Gly‐(Z)‐ΔPhe‐NHMe has a great tendency to adopt β‐turn conformation. In the gas phase the type II β‐turn is preferred, whereas in the polar environment, the type I. On the other hand, dehydro residue in Ac‐Gly‐(E)‐ΔPhe‐NHMe has a preference to adopt extended conformations in all environments. N‐methylation of C‐terminal amide group, which prevents the formation of 1←4 intramolecular hydrogen bond, change dramatically the conformational properties of studied dehydropeptides. Especially, the tendency to adopt β‐turn conformations is much weaker for the N‐methylated Z isomer (Ac‐Gly‐(Z)‐ΔPhe‐NMe₂), both in vacuo and in the polar environment. On the contrary, N‐methylated E isomer (Ac‐Gly‐(E)‐ΔPhe‐NMe₂) can easier adopt β‐turn conformation, but the backbone torsion angles (?₁, ψ₁, ?₂, ψ₂) are off the limits for common β‐turn types. © 2012 Wiley Periodicals, Inc. Biopolymers 97:518–528, 2012.     

Influence of proline and β-turn mimetics on the cyclization of penta- and hexapeptides

Summary Proline and Pro-derived peptidomimetics, such as meoxPro-Oic (4-methoxy-proline-octahydro indolic acid), and DBF (2-aminoethyl-6-dibenzofuran propionic acid) were introduced into thymopentin-derived penta-[SP5-] and hexa-[SP6-] peptides and penta-, hexa- and hepta-alanine. Surprisingly, we found that cyclomonomer formation in the investigated penta- and hexapeptides was drastically hindered by the presence of proline regardless of position.     

Structural and functional mapping of α-fetoprotein

Alpha-fetoprotein (AFP) is a major mammalian oncofetal protein, which is also present in small quantities in adults. It is a member of the albuminoid gene superfamily, which consists of AFP, serum albumin, vitamin D binding protein, and alpha-albumin (afamin). Although physicochemical and immunological properties of AFP have been well-studied, its biological role in embryo- and carcinogenesis and in adult organisms as well as mechanisms underlying its functioning remain unclear. During the recent decades, the biological role of AFP has been evaluated by identification of its functionally important sites. Comparison of primary structure of AFP and some physiologically active proteins revealed similarity of some polypeptide regions. This has been used for prediction of AFP functions (i.e., its multifunctionality). Localization of functionally important sites followed by determination of their amino acid composition and type of biological activity has provided valuable information for structural-functional mapping of AFP. Some peptide fragments of AFP have been synthesized and tested for biological activity. This review summarizes data on structural-functional interrelationships. We also describe functionally important AFP sites found by various groups during the last decade of structural-functional mapping of AFP with experimentally confirmed and putative biologically active sites.     

Reconsidering the importance of the past in predator–prey models: both numerical and functional responses depend on delayed prey densities

We propose that delayed predator–prey models may provide superficially acceptable predictions for spurious reasons. Through experimentation and modelling, we offer a new approach: using a model experimental predator–prey system (the ciliates Didinium and Paramecium), we determine the influence of past-prey abundance at a fixed delay (approx. one generation) on both functional and numerical responses (i.e. the influence of present : past-prey abundance on ingestion and growth, respectively). We reveal a nonlinear influence of past-prey abundance on both responses, with the two responding differently. Including these responses in a model indicated that delay in the numerical response drives population oscillations, supporting the accepted (but untested) notion that reproduction, not feeding, is highly dependent on the past. We next indicate how delays impact short- and long-term population dynamics. Critically, we show that although superficially the standard (parsimonious) approach to modelling can reasonably fit independently obtained time-series data, it does so by relying on biologically unrealistic parameter values. By contrast, including our fully parametrized delayed density dependence provides a better fit, offering insights into underlying mechanisms. We therefore present a new approach to explore time-series data and a revised framework for further theoretical studies.     

Structural and functional studies on ø29 DNA polymerase

TheBacillus subtilis phage ø29 DNA polymerase, involved in protein-primed viral DNA replication, contains several amino acid consensus sequences common to other eukaryotic-type DNA polymerases. Using site-directed mutagenesis, we have studied the functional significance of a C-terminal conserved region, represented by the Lys-X-Tyr (“K-Y”) motif. Single point mutants have been constructed and the corresponding proteins have been overproduced and characterized. Measurements of the activity of the mutant proteins indicated that the invariant Lys and Tyr residues play a critical role in DNA polymerization. Interestingly, substitution of the invariant Lys either by Arg or Thr, produced enzymes with an increased or a largely reduced, respectively, capability to use a protein as primer, an intrinsic property of TP-priming DNA polymerases. On the other hand, the viral protein p6, which stimulates initiation of ø29 DNA replication by formation of a nucleoprotein complex at both DNA replication origins, increased (about 5-fold) the insertion fidelity of ø29 DNA polymerase during the formation of the TP-dAMP initiation complex. We propose a model in which the special strategy to maintain the integrity of the ø29 DNA ends, by means of a “sliding-back” mechanism, could also contribute to increase the fidelity of ø29 DNA replication.     

14. Studies on Poliomyelitis Virus—Concentration and Purification of the Virus

ABSTRACT

For the purpose of determining the immunogenic potency of polio virus, relatively large amounts of concentrated virus material were prepared which had titres of the order of 10¹⁰ T.C.I.D.jo per ml. These were obtained by pervaporating large quantities of tissue culture fluid containing approximately 10⁶⁵ T.C.I.D.JQ per ml.     

Studies on the metabolism of steroids in the foetus. Biosynthesis of 6α-hydroxytestosterone in the human foetal liver

After incubation of testosterone with 105000g microsomes of human foetal liver, 6alpha-hydroxytestosterone was isolated and identified by t.l.c. and g.l.c.-mass spectrometry. This is the first example of 6alpha-hydroxylation of C(19) steroids in the human liver, and the finding is discussed in relation to earlier reports of 6-oxygenated C(19) and C(18) steroids in pregnant women.     

Investigations on the role of π–π interactions and π–π networks in eNOS and nNOS proteins

π–π Interactions play an important role in the stability of protein structures. In the present study, we have analyzed the influence of π–π interactions in eNOS and nNOS proteins. The contribution of these π–π interacting residues in sequential separation, secondary structure involvement, solvent accessibility and stabilization centers has been evaluated. π–π interactions stabilize the core regions within eNOS and nNOS proteins. π–π interacting residues are evolutionary conserved. There is a significant number of π–π interactions in spite of the lesser natural occurrences of π-residues in eNOS and nNOS proteins. In addition to π–π interactions, π residues also form π–π networks in both eNOS and nNOS proteins which might play an important role in the structural stability of these protein structures.