Myosin heavy chains in fast skeletal muscle of chick embryo

Summary The peptide map obtained by electrophoresis after digestion of purified myosin heavy chains from pectoralis muscle of embryonic chicken with theStaphylococcus aureus V8 protease, produces a peptide pattern very similar but not identical to that of adult fast myosin. In fact, some components that are present in a small amount in the map of slow adult myosin are visible in the embryonic pattern.Acknowledgments. I wish to acknowledge the enthusiastic encouragement of Dr Ugo Carraro and the help of Prof. Stefano Schiaffino's group and of Dr Marcello Cantini for embryonic tissue isolation. The skillful technical assistance of Mr Silvio Belluco is also gratefully acknowledged. This work was supported in part by a grant of Muscular Dystrophy Association of America to Prof. Massimiliano Aloisi.     

Effect of phosphorylation of myosin light chains on interaction of heavy meromyosin with regulated F-actin in ghost fibers

The binding of phosphorylated heavy meromyosin to regulated F-actin in ghost fibers at high Ca2+ concentration increases, and at low Ca2+ concentration decreases, the anisotropy of intrinsic tryptophan fluorescence of F-actin. The effect is opposite to the effect of the binding of dephosphorylated heavy meromyosin.     

Effect of phosphorylation of myosin light chains on interaction of heavy meromyosin with regulated F-actin in ghost fibers

Summary The binding of phosphorylated heavy meromyosin to regulated F-actin in ghost fibers at high Ca²⁺ concentration increases, and at low Ca²⁺ concentration decreases, the anisotropy of intrinsic tryptophan fluorescence of F-actin. The effect is opposite to the effect of the binding of dephosphorylated heavy meromyosin.     

A simple check of the time homogeneity of Markov chains

In this paper we consider a population where the state of each individual follows a Markov chain. If the population is recorded for a very few periods only, it is still possible to estimate the transition matrix and to make projections into the far future. These forecasts are sensible if the chains are time homogeneous, but this is difficult to check if only a few periods are observed. We suggest a simple method to check this assumption, and obtain an upper bound on the time the process can have been time homogeneous. The method is also applied to a second-order Markov chain and to the mover-stayer model. AMS subject classification (1980): Primary 62M05, Secondary 62M20.     

Immunoglobulin light chains, glycosaminoglycans, and amyloid

Immunoglobulin light chains are the precursor proteins for fibrils that are formed during primary amyloidosis and in amyloidosis associated with multiple myeloma. As found for the approximately 20 currently described forms of focal, localized, or systemic amyloidoses, light chain-related fibrils extracted from physiological deposits are invariably associated with glycosaminoglycans, predominantly heparan sulfate. Other amyloid-related proteins are either structurally normal, such as beta2-microglobulin and islet amyloid polypeptide, fragments of normal proteins such as serum amyloid A protein or the precursor protein of the beta peptide involved in Alzheimer's disease, or are inherited forms of single amino acid variants of a normal protein such as found in the familial forms of amyloid associated with transthyretin. In contrast, the primary structures of light chains involved in fibril formation exhibit extensive mutational diversity rendering some proteins highly amyloidogenic and others non-pathological. The interactions between light chains and glycosaminoglycans are also affected by amino acid variation and may influence the clinical course of disease by enhancing fibril stability and contributing to resistance to protease degradation. Relatively little is currently known about the mechanisms by which glycosaminoglycans interact with light chains and light-chain fibrils. It is probable that future studies of this uniquely diverse family of proteins will continue to shed light on the processes of amyloidosis, and contribute as well to a greater understanding of the normal physiological roles of glycosaminoglycans.     

Role of lysine side chains in metallothionein

Summary pK_a-Values of lysine residues of mammalian metallothionein were determined by chemical titration measurements of -CH₂ lysine resonances in the¹H-NMR spectra. They are about 0.5 pH-unit higher than the average pK_a-value of a metal-free derivative, suggesting interaction of the positively charged residues with the two three-fold negatively charged metal-thiolate clusters of the metal-containing form. Deprotonation of the lysines leads to circular dichroism changes attributable to an electrostatically induced structural transition of the protein.To whom correspondence concerning this paper should be addressed.     

Polyubiquitin chains: functions, structures, and mechanisms

Ubiquitin is a highly conserved 76-amino acid polypeptide that is found throughout the eukaryotic kingdom. The covalent conjugation of ubiquitin (often in the form of a polymer) to substrates governs a variety of biological processes ranging from proteolysis to DNA damage tolerance. The functional flexibility of this post-translational modification has its roots in the existence of a large number of ubiquitinating enzymes that catalyze the formation of distinct ubiquitin polymers, which in turn encode different signals. This review summarizes recent advances in the field with an emphasis on the non-canonical functions of polyubiquitination. We also discuss the potential mechanism of chain linkage specification as well as how structural disparity in ubiquitin polymers may be distinguished by ubiquitin receptors to translate the versatile ubiquitin signals into various cellular functions.     

Effect of heavy physical training on the catecholamine content of the heart and adrenals of the guinea-pig

Zusammenfassung Ein langdauerndes Training bewirkt keine Herabsetzung der Catecholamine in Herz und Nebennieren des Meerschweinchens.

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This work has been supported by a grant from Svenska Nationalföreningen mot Hjärt- och Lungsjukdomar.     

Anomaly of the polypeptide and oligosaccharide chains of alpha-2-neuraminoglycoprotein in various types of hereditary angioneurotic edema

Using two-dimensional immuno-electrophoresis to study a morphological abnormality of the alpha 2-neuramino-glycoprotein (alpha 2-NGP) we have been able to observe allelic exclusion in patients afflicted by hereditary angioneurotic oedema [1]. With the aid of two-dimensional immuno-affino-electrophoresis, we have been able to show that in some cases, there exists a double abnormality of alpha 2-NGP associating a deficiency in post translating glycosylation with a loss of the inhibitory function of the C1 esterase.     

Hybrid formation in mixtures of hemoglobins and isolated hemoglobin chains from different species

Riassunto Miscele di emoglobina canina e catene isolate di emoglobina umana, tenute a pH neutro e a bassa forza ionica, mostrano la formazione di molecole ibride. La formazione di ibrido in tampone fosfato diluito è minore che in assenza di sali.