It is well established that the glycans in glycoproteins are often involved in important biological phenomena. To understand the role of the glycans attached to glycoproteins in solution, structural information obtained by NMR spectroscopy is obviously required. Recently we have developed a systematic stable isotope labeling method for NMR study of glycoprotein glycan. We have applied this labeling method to Fc fragment of immunogloblin G, with a molecular weight of 50K. Here we describe the labeling strategy and briefly discuss the structures and functions of glycans attached to Fc fragment.
The characteristic 450 nm spectrum of cytochrome P450 is highly sensitive to denaturation of the protein structure. It is a sensitive indicator of the native conformation of the heme-containing catalytic domain of P450 molecules, and can be conveniently utilized in studying the mechanism of folding of P450 proteins in the cell. Microsomal forms of cytochrome P450 have a short proline-rich sequence following the N-terminal signal-anchor sequence. Similar proline-rich sequence is also found in the N-terminal region of the mature forms of mitochondrial P450s and some soluble bacterial P450s. The proline-rich sequence has been shown to be important for efficient folding of newly synthesized P450 proteins in Escherichia coli cells as well as in eukaryotic cells. The mechanism of participation of the proline-rich sequence in the folding of newly synthesized P450 peptides is not yet clarified.
This report presents the computer simulation of a self-organizing system of mutually locked oscillators. It indicates that this many-oscillator system behaves like an amoeboid cell. This result suggests the organization of the amoeboid movement is related to the function of the oscillation induced by mitochondoria.
Molecules of bacteriochlorophyll a(BChl a), as well as its derivatives, formed assemblies with the presence of light-harvesting(LH)polypeptides, isolated from photosynthetic bacteria, or its synthetic model polypeptides. Spectroscopic properties of BChl a derivatives in the complex with LH model polypeptides were analogous to those with LH polypeptides from photosynthetic bacteria. It is interesting to note that the cooperative interactions between LH polypeptide(or its model polypeptides)and BChl a(or its derivatives)can cause complex formation.
Physics of protein folding developed by late Toyoichi Tanaka, who offered his devotion to breaking the life's second code, is described and its significance to the thermodynamical law in nature and evolution is studied. Particularly his extended formalism for canonical emsemble dedicated to overcome the very different time-scales characterizing protein folding and evolution is discussed.