Life, it seems, really is a lottery. …Once we grasp how improbable our existence is, once we realize that we have won the jackpot in the lottery of life, and once we sense how precarious this precious existence is when nature does not care whether our imaginations and feelings survive or not, perhaps we shall learn to cherish human life more carefully ourselves. (Nigel Calder)1)
This short article focussed on several recent experiments about modification of the potassium ion pathway of sodium/potassium-transport ATPase of animal cell membranes. Hydrophobic pyridin derivative, AU-1421 is a fluorecsent probe and is expected to bring about much information from its binding site.
A number of studies on the mechanism of uncoupler action appear to be incompatible with the chemiosmotic hypothesis which assumes that bulk proton electrochemical gradient (ΔμH) is the only intermediate linking between oxidation and phosphotylation in mitochondria. Decouplers such as general anesthetics seem to induce uncoupling by releasing protons from intramembrane proton pathway or inducing the proton slip of proton pumps. Uncoupling by weakly acidic uncouplers could be a mixture of the collapse of ΔμH and the decoupling (or proton sliping).
Transcription of human adenovirus genes is regulated by a variety of cellular and viral transcription factors. We described in this issue recent informations of adenovirus E1A proteins, and cellular factors, TF II D, ATF/E4TF3, E2F, E4TF1 and USF, responsible for transcription of adenovirus genes. In addition to the transcription factors, we introduced a newly concept of initiator, which is a transcription control element of adenovirus major late promoter.
Recently, the molecular recognition by monoclonal antibodies has been utilized widely in the field of organic chemistry. In this article. application of monoclonal antibodies in photochemistry was reviewed. Attention was focused on a photoreversible uptake and release of photochromic hapten peptides and on a photopatterning of antibodies on a surface carrying hapten peptides.
Progress in the studies of visual pigment rhodopsin using retinal anaiogues is reviewed. At first, the external point-charge model based on the hydrorhodopsin data was presented to explain the wavelength regulation in visual pigments. In order to clarify the primary photochemical event by chemical methods, two types of rhodopsin analogues [(3) and (4)] were synthesized. The former (3) was derived from 9-cis-retro-γ-retinal (5) possessing two separated chromophore systems. The latter (4) was prepared from 11-cis-locked-cyclopentatrienylidene retinal analogue (6). Photochemical studies of these analogues showed that an 11-cis to 11-trans isomerization is a pre-requisite for visual transduction. The same confirmation was also obtained by employing a cycloheptatrienylidene rhodopsin (27). Comparison of the CD data for (4), rhodopsin, and (27) demonstrated that the a-CD band of rhodopsin has its origin in the twisted 12s-trans-conformation in the chromophore. Subsequently, in order to investigate the origin of β-CD band of rhodopsin, 6s-cis-locked-and6s-trans-locked-bicyclic rhodopsins [(51) and (52)] were synthesized.
Molecular dynamics simulations are widely used to investigate various properties of proteins. For obtaining reliable results, however, molecular dynamics simulations have serious problems to be solved. Recently, the most difficult problem (truncation of long-range coulomb interactions) has been overcome. The reliability of molecular dynamics simulations has remarkably increased.
An introduction to theoretical developmental biology is presented. Molecular aspects on the axis determination and segmentation of Drosophila embryo were summarized and dicussed from a theoretical point of view.