Myosin is one of the key protein components of biological force generating systems. The globular head region of the myosin molecule, subfragment-1 (S-1), contains the site for ATP binding and hydrolysis and the site for actin binding. Although the open and closed conformational states of the ligand-binding pocket have been well established with various proteins other than myosin, such an operation of the ATP-binding pocket of S-1 is purely speculative at present. A hydrophobic fluorescent dye was found to bind to the ATP-binding pocket of S-1. Fluorescence study reveals that the ATP-binding pocket of S-1 is closed and/or tightened during ATP hydrolysis.
In nervous system, neurons are surrounded with glial cells as schwann cell (in peripheral nervous system), oligodendorocyte (in central nervous system), astorocyte, microglia, and epitherial cells. Recently, it has been reported that glial cells have several ion channels, neurotransmitter receptors and secrete neurotrophic factors and cytokines. So these indicate that glial cells have roles not only to support neurons but also to mediate neuronal survival, regeneration and neuronal activities. In this review we introduce some recent informations about glial cells.
A hemoglobin-like protein is present in some of the single-celled organisms, but its structure is quite different from that of mammalian myoglobin or hemoglobin. For instance, a protozoan myoglobin isolated from Paramecium caudatum consists of 116 amino acid residues, so that this contracted form is nearly two thirds of sperm whale myoglobin. Yeast hemoglobin from Candida norvegensis, on the other hand, is composed of a single polypeptide chain of 387 amino acid residues, but of two distinct domains carrying different functions; that is the N-terminal, heme-containing region and the C-terminal, FAD-containing reductase domain.
Infrared spectroscopy is a suitable technique to analyze the structure and function of the binuclear metal site of the heme-copper respiratory terminal oxidase. Successfull examples for cytochrome c oxidase and cytochrome bo complex from Escherichia coli using various respiratory inhibitors including carbon monoxide (CO), cyanide (CN) and azide (N3) as monitoring probes are discussed.