Das Gesetz der absoluten Geschwindigkeiten biologischer Prozesse

The dependency of the velocity of biological processes from the temperature is described by the “Law of absolute velocity of biological processes”, which has only the individual parameters energy of activation ΔE, and the universal constant C. The law holds for all biological processes and is expressed by the equation: where C is: .     

Bioactive peptides: Conformational study of a cystinyl cycloheptapeptide in its free and calcium complexed forms

The disulphide bridged heptapeptide has been synthesized by classical solution methods. An ion binding study showed the peptide's ability to complex calcium ions with definite stoichiometry. The solution conformation of the peptide in its free and calcium-complexed form has been investigated by CD and nmr. The model structure derived from nmr data has been energy minimized and the resulting structure investigated by molecular dynamics simulation in water. The structure of the equimolar peptide/Ca^2? complex in acetonitrile at room temperature shows the presence of two transannular hydrogen bonds, with the formation of two ring structures of the C₁₀ (type VIa) and C₁₄ type. One peptide unit (Pro-Pro) is cis, all others are trans. © 1993 John Wiley & Sons, Inc.     

Transfer function matrix of the continuous cultivation system of Morchella crassipes in ammonia base waste sulfite liquor

A continuous stirred tank fermentor (CSTF) used for cultivation of the fungus Morchella crassipes in ammonia base waste sulfite liquor (NH₃-WSL) was considered as a multivariable linear system around its operating point. Pulse testing on the inputs (inlet jacket temperature, inlet pH, inlet substrate concentration) and their responses at the outputs (biomass, outlet temperature, outlet jacket temperature, outlet pH, outlet substrate concentration) were used for numerical determination of the transfer function matrix:      

Issue Information

Cover Photograph: A SEM micrograph of developing PGCs in the genital ridge of Columba livia (see Olea et al. pp 56-65).

     

Cystine peptides: the intramolecular antiparallel beta-sheet conformation of a 20-membered cyclic peptide disulfide

A 20-membered cyclic peptide disulfide has been synthesized as a conformational model for disulfide loops of limited ring size. ¹H-nmr studies at 270 MHz establish the presence of three intramolecular hydrogen bonds involving the Leu, Val, and methylamide NH groups in CDCl₃. Evidence for peptide aggregation in CDCl₃ is also presented. A structural transition involving loosening of the hydrogen bond formed by the Val NH group is observed upon the measured addition of (CD₃)₂SO to CDCl₃. Hydrogen-bonding studies, together with unusually low field positions of the Cys(1) and Cys(6) C^αH resonances and high J values provide support for an intramolecular antiparallel β-sheet conformation, facilitated by a chain reversal at the Aib-Ala segment. Extensive nuclear Overhauser effect studies provide compelling evidence for the proposed conformation and also establish a type I′ β-turn at the Aib-Ala residues, the site of the chain reversal.     

Depolarized light scattering by amides and peptides

The Rayleigh ratios R_H have been measured for the depolarized scattering dilute solutions of N-ethylacetamide (EA), N-methylpropionamide (MP), and N-acetyl-pyrrolidine (AP) in P-dioxane, and dilute aqueous solutions of N-methylacetamide (MA), N,N-dimethylacetamide (DMA), EA, and MP. Squares of the optical anisot-ropies γ of the amides are obtained through extrapolation of these mesurements to infinite dilution. Values of γ² found for EA and MP in dioxane are in good agreement with calculations based principally on the previously evaluated polarizability tensor of the amide group in conjunction with C? C and C? H bond polarizabilities. The calculations also involve averaging over all conformations, each being weighted according to the estimated conformational energy. The mean-squared optical anisotropies (γ²) of the oligoglycines and oligoalanines are calculated by similarly averaging over all skeletal conformations. The anistropic polarizability tensor \documentclass{article}\pagestyle{empty}\begin{document}$ \hat \alpha $\end{document} for the prolyl structural unit is derived for γ² for AP. The much larger optical anisotropies exhibited by the amides when dissolved in water as compared with those observed in dixane are discussed.     

Solution structure and dynamics of a glycoinositol phospholipid (GIPL-6) from Leishmania major

By use of a combination of ¹H nuclear Overhauser effect measurements, restrained molecular dynamics simulations, and ¹³C spin–lattice relaxation time measurements, the solution behavior of the glycan moiety of a complex glycoinositol phospholipid termed G1PL-6, from the protozoan parasite Leishmania major has been determined. The glycan moiety of GIPL-6 has the following structure, which is characterized by the presence of an internal β-galactofuranose residue: The glycan does not adopt a single conformation in solution, due to significant torsional variations about the two phosphodiester linkages and certain glycosidic linking in the molecule. The present of the internal galactofuranose residue results in an average solution conformation of the oligosaccharide, which resembles a “hairpin,” with the galactofuranose residue at the apex. © 1994 John Wiley & Sons, Inc.     

Confidence Estimation of an Unknown Component of the Vector of Regressor Variables in Multivariate Linear Regression

The model used in this paper is Y = Xβ, where with unknown x₀. Estimators of x₀ are derived by putting β_mx₀ =β_m+1 regarding β_m+1 as a new unknown parameter. Formally we use the model Y = X₁β₊ + e where β′₊ = (β₀, …β_m+1 and Then β_m+1/ β_m is a point estimator of x₀. Assuming normality for e and taking the random variable z=β_mx₀?β_m+1 we get a t-distributed variable and finally a confidence estimator of x₀. The formulas are applied in dose response relations in antibiotic assays refering to a standard. Now we can take into account not only the dependence on the dose/concentration but also on the position on the test agar plate where the test solution is filled in. As a consequence the confidence interval of the unknown dose/concentration x₀ becomes shorter and by it the statements more precise.     

On the Effects of Departure from Normality on the F-Ratios in a Nested Random Effect Model by Mixture of Normals

In this paper we consider the following nested random effect model where the α_i's, the β_ij's and the e_ijk are independent random variables. By assuming that these variables follow a mixture of two normal densities, we study the effects of departure from normality on the classical JT-tests for variance components. It is shown that the departure from normality has little effects on the type 1 error and the power function; this indicates that the classical F-tests are quite robust with respect to departure from normality.     

Issue Information

The estimated life span of Halimeda from a new recruit to a fertile plant. See Mayakun and Prathep in this issue. Cover picture from: Article link here

     

Issue Information

In situ photograph of Lobophora coquilleae sp. nov. from Papua New Guinea. See Vieira et al. in this issue. Cover picture from: Article link here

     

Etude par spectroscopie infrarouge de la transformation hélice–chaîne statistique des polypeptides. II. Etude de l'interaction de quelques polypeptides à chaînes latérales polaires avec l'acide trifluoracétique

The various polymer–acid solvation possibilities occuring in the helix–coil transition process of polypeptides with polar side chains were systematically analyzed by infrared spectroscopy. The following samples have been considered: poly-γ-benzyl-L -glutamate (PBLG), alternating poly-γ-benzyl-D ,L -glutamate (PBD-LG), and poly-β-benzyl-L -as-partate (PBLA). The behavior of the amide A, I, II, and νC?O ester absorptions of each polymer dissolved in trifluoroacetic acid–chloroform mixtures was studied in depth. The classical assumptions concerning the interaction between a polypeptide and a proton donor solvent are discussed. This interaction was previously proposed in a theoretical model of helix–coil transition. For PBLG, the spectral characteristics of the cooperative transition are evidenced by the amide bands. These bands also show main chain–acid hydrogen bonding (I) Quantitative analysis of phenomenon (I) was performed in order to localize the “binding sites” of the polymer. In agreement with the theory, only the complexation of peptide units belonging to random coil and terminal helical regions were observed. However, in contrast to the theory in which the association constants KCO and KNH of these residues are generally kept equal, the present results have shown that the main binding site is the carbonyl group (KNH ? 0 or « KCO ). The behavior of the polar side chains of these polypeptides were analyzed during the transition. Similarly to the peptide backbone, they bind the acid by hydrogen bonding (II) Furthermore, this association is more important when the side chains are localized in the coiled regions than in the helical ones. This result suggests, by analogy with the main chain behavior, that the helix–coil transition theory should take into account two more association constants for polar side chains, namely k₁ for the helical regions and k₂ > k₁ for the coiled ones.     

News & ISN April 2019

We are very sad that the ISN lost its President Kazuhiro Ikenaka, Professor and Chairman at National Institute for Physiological Sciences (NIPS), Director of Okazaki Institute of Integrative Biology. JNeurochem published an Obituary to value his outstanding achievements: Akio Wanaka et al. (2019) OBITUARY Kazuhiro Ikenaka (1952‐2018). https://doi.org/10.1111/jnc.14679

     

Protein misfolding cyclic amplification induces the conversion of recombinant prion protein to PrP oligomers causing neuronal apoptosis

The formation of neurotoxic prion protein (PrP) oligomers is thought to be a key step in the development of prion diseases. Recently, it was determined that the sonication and shaking of recombinant PrP can convert PrP monomers into β‐state oligomers. Herein, we demonstrate that β‐state oligomeric PrP can be generated through protein misfolding cyclic amplification from recombinant full‐length hamster, human, rabbit, and mutated rabbit PrP, and that these oligomers can be used for subsequent research into the mechanisms of PrP‐induced neurotoxicity. We have characterized protein misfolding cyclic amplification‐induced monomer‐to‐oligomer conversion of PrP from three species using western blotting, circular dichroism, size‐exclusion chromatography, and resistance to proteinase K (PK) digestion. We have further shown that all of the resulting β‐oligomers are toxic to primary mouse cortical neurons independent of the presence of PrP^C in the neurons, whereas the corresponding monomeric PrP were not toxic. In addition, we found that this toxicity is the result of oligomer‐induced apoptosis via regulation of Bcl‐2, Bax, and caspase‐3 in both wild‐type and PrP^?/? cortical neurons. It is our hope that these results may contribute to our understanding of prion transformation within the brain.

     

Inside Cover: Raman ChemLighter: Fiber optic Raman probe imaging in combination with augmented chemical reality (J. Biophotonics 7/2019)

The newly developed Raman ChemLighter allows the real‐time acquisition of spectroscopic data using a handheld probe. By intelligently combining the fiber‐based imaging approach with computational modeling, we can directly extract molecular information of a sample provide augmented chemical reality to visualize chemistry. Further details can be found in the article by Wei Yang, Abdullah S. Mondol, Clara Stiebing, Laura Marcu, Jürgen Popp, Iwan W. Schie ( e201800447 ).

     

Potentiometric neutralization of oligomers represented by the general formula shown was studied. II (author's transl)

Potentiometric neutralization of oligomers represented by the general formula shown was studied. The intrinsic pK of carboxyl function was found to be 4.40 at 25°C; the variation of the apparent pK_a, ΔK(α), was studied as a function of the degree of neutralization: the influence of the degree of neutralization on the accumulation of ionic sites along the chain is clearly shown. The experimental curves of polyglutamic acid allowed us to deduce the sequence of ionic selectivity and the energy of conformational transition. The theoretical interpretation of the results was proposed in terms of the rod like model from Katchalsky's theory. The intrinsic pK_o for the polymer was set equal to the value experimentally obtained on oligomers. By activity measurements on Na⁺ and Ca²⁺ counterions in salt-free solutions, the free fraction of counterions was deduced on the different samples. The results were interpreted with the electrostatic model previously proposed; in this view, the oligomers are assimilated to imaginary polyelectrolytes. This allowed us to determine the values of ΔpK and the fraction of free ions at the same time.     

Inside Cover: Three‐dimensional intravital imaging in bone research (J. Biophotonics 12/2019)

This review is aimed at interpreting development and advantages of intravital imaging as an emerging invaluable methodology and summarizing related representative discoveries in bone physiologies and pathologies. It also indicates current limitations, further refinement, and extended application of intravital imaging in bone research. Further details can be found in the article by Yuhao Liu, Quan Yuan, and Shiwen Zhanget ( e201960075 ).