The protein formula of beef heart cytochrome c oxidase

Beef heart cytochrome c oxidase consist of 12 different polypeptides stoichiometrically arranged in respiratory complex IV. The functional 2 heme a, 2 copper monomer of this complex consist of 1793 amino acids; the exact Mr is 202,787 Da. From 17 cysteine residues, six are involved in the formation of three disulphide bonds. The theoretical heme a content of the enzyme is 9.86 nmol/mg protein. The theoretical iron and copper contents are 0.55 and 0.63 microgram/mg protein, respectively.     

Localization of lipid binding domain(s) on subunit II of beef heart cytochrome c oxidase

Photoactivatable arylazido phospholipids (Bisson, R., and Montecucco, C. (1981) Biochem. J. 193, 757-763) have been used to study the arrangement in the membrane of beef heart cytochrome c oxidase subunit II. Fragmentation of the photocross-linked polypeptide showed that sequence 20-98, which contains two long stretches of uncharged amino acid residues (Steffens, G. J., and Buse, G. (1979) Hoppe-Seyler's Z. Physiol. Chem. 360, 613-619), is in contact with lipids. Edman degradation of the labeled peptide indicated that His 26, Thr 27 and Met 29 are involved in the interaction with the polar head region of the bilayer. These data have been used to propose a scheme for the folding of subunit II in the mitochondrial membrane.     

Heat balance of the human body: influence of variations of locally distributed parameters

Human body temperature control is characterized by a local dependence of system variables and parameters. Essential properties regarding inhomogeneity of the passive system have been investigated using mathematical methods. The general diffusion-equation has been solved using implicit finite difference methods with nonlinear boundary conditions. In order to allow comparison with experimental results, a simple ideal controller has been defined. On the basis of an inhomogeneous cylinder model with four concentric layers, influences of variations due to differences between tissues and individuals or measurements of parameters such as basal metabolism and conductivity have been studied. Stationary temperature profiles calculated for homogeneous and inhomogeneous conditions have been compared. Finally, the influence of blood flow has been discussed, as well as the stationary behaviour of profiles due to blood flow and blood flow control. The change of sign of curvature of temperature profile is possible only if blood flow mechanisms and the local distribution of metabolism are taken into account.     

Effect of fasting, branched-chain amino acids, and glucocorticoids on histone H1 extractability from rat skeletal muscle.

The effect of 72 h fasting, nutritional therapy of fasted rats, and acute and chronic glucocorticoid treatment on the yield of histone H1 from rat hind limb muscles was determined. Fasting significantly enhanced the extractability of muscle H1. The effect of treating starved rats with glucose alone, or with glucose supplemented with branched-chain amino acids (BCAA), or with two commercial preparations of mixtures of essential and non-essential amino acids was evaluated. Treatment of starved rats with glucose alone significantly decreased H1 extractability from muscles, but isocaloric treatment with glucose supplemented with BCAA or two commercial preparations of amino acid mixtures was more effective. Glucocorticoid treatment for 5 days enhanced the yield of H1 from muscles less than starvation. The enhanced H1 extractability from muscles noted in starved rats is similar to that reported in rats with insulinopenic diabetes and may reflect changes in nuclear fragility.     

Transpeptidation in sequence analysis. Investigations concerning a native and a synthetic hexapeptide.

On sequencing a hemoglobin a peptic hexapeptide with the amino acid composition Asp2, Gly, Val, Lys2 was isolated. Cleavage of this peptide with Tos-Phe-CH2Cl-trypsin resulted in the fragments Asp-Lys, Gly-Asp, Val-Lys, Asp--Lys-Gly-Asp, Asp-Lys-Val-Lys and Val-Lys-Gly--Asp. From these data two possible but inconsistent sequences for the hexapeptide can be derived: Asp-Lys-Val-Lys-Gly-Asp and Val-Lys-Asp-Lys-Gly-Asp. Fragments obtained by other cleavage procedures, direct sequencing of the globin peptide-chain with a sequenator as well as X-ray data of this hemoglobin show, that only the sequence starting with Asp occurs in the intact protein. Therefore the peptide Asp-Lys-Gly-Asp must have been formed by transpeptidation during sequence work. In order to verify this, Asp-Lys-Val-Lys-Gly-Asp was synthesized by an unequivocal, conventional procedure. Tryptic digestion of this hexapeptide also resulted in ASP-Lys-Gly-Asp in addition to the expected fragments. Thus it has been shown for the first time, that sequencing conditions may alter the constitution of a peptide.     

Arachidonic acid metabolites and colchicine in Behçet's disease (BD)

Vasculitis is accepted to be the basis of Behçet's disease (BD) which is a multisystem disease, and the arachidonic acid(AA) metabolites acting as balancing mediators in the organism are accepted to be responsible for the vasculitis.In this study, we examined the prostaglandin E₂ (PGE₂) and leukotriene C₄ (LTC₄) levels of the patients with BD before and after colchicine therapy. We found a statistical decrease in the PGE₂ and LTC₄ levels after colchicine therapy compared to the previous levels, concluding that colchicine inhibits the inflammation and the polymorphonuclear leukocyte (PML) chemotaxis by inhibiting the cyclooxygenase and lipoxygenase patways.