Proteins in bioelectricity: the control of ion movements across excitable membranes

Computational interaction analysis of organophosphorus pesticides with different metabolic proteins in humans

Pesticides have the potential to leave harmful effects on humans, animals, other living organisms, and the environment. Several human metabolic proteins inhibited after exposure to organophosphorus pesticides absorbed through the skin, inhalation, eyes and oral mucosa, are most important targets for this interaction study. The crystal structure of five different proteins, PDBIDs: 3LII, 3NXU, 4GTU, 2XJ1 and 1YXA in Homo sapiens (H. sapiens), interact with organophosphorus pesticides at the molecular level. The 3-D structures were found to be of good quality and validated through PROCHECK, ERRAT and ProSA servers. The results show that the binding energy is maximum -45.21 relative units of cytochrome P450 protein with phosmet pesticide. In terms of H-bonding, methyl parathion and parathion with acetylcholinesterase protein, parathion, methylparathion and phosmet with protein kinase C show the highest interaction. We conclude that these organophosphorus pesticides are more toxic and inhibit enzymatic activity by interrupting the metabolic pathways in H. sapiens.

Chemical events in conducting and synaptic membranes during electrical activity

Evidence has accumulated in recent years for the central role of proteins and enzymes in the function of cell membranes. In the chemical theory proposed for the generation of bioelectricity, i.e., for the control of the ion permeability changes of excitable membranes, the protein assembly associated with the action of acetylcholine plays an essential role. Support of the theory by recent protein studies in which the excitable membranes of the highly specialized electric tissue were used will be discussed. A scheme is presented indicating the possible sequence of chemical reactions that change ion permeability after excitation. A sequence of chemical events within the excitable membranes of the synaptic junctions, i.e., within the pre- and postsynaptic membranes, similar to that proposed for the conducting membranes, is presented in a second scheme as an alternative to the hypothesis of the role of acetylcholine as a transmitter between two cells.

[Evidence of a neurohormone in moss callus and its regulation by the phytochrome]

The presence of a neurohormone in moss callus could be demonstrated by means of pharmacological experiments on the heart of the frog (Rana temporaria L.) and by chromatography.The hearts react in the same manner as they do to application of acetylcholine and the substance resembles acetylcholine in its Rf-value. Therefore it is suggested that this hormone is identical with acetylcholine. The concentration of the hormone in the callus cells is mediated by the phytochrome. Moss callus cultivated under red and far-red illumination contain less substance than moss callus grown in red light.

Evidence for the regulation of phytochrome-mediated processes in bean roots by the neurohumor, acetylcholine

Using pharmacological and chromatographic techniques, it was shown that acetylcholine was present in all organs of both light- and dark-grown mung bean seedings (Phaseolus aureus). The highest concentrations were found in tissues containing active growing points: buds and secondary roots. Within 4 minutes, red light caused an increase in the efflux of acetylcholine from secondary root tips as well as a significant increase in the endogenous titer. Four minutes of subsequent far red light reduced the latter to a level comparable to that in the dark.Acetylcholine, given for 4 minutes in the dark, was able to substitute for red light in reducing the formation of secondary roots, inducing increased H(+) efflux, and causing the root tips to adhere to a negatively charged glass surface. Acetylcholine-esterase and atropine inhibited the latter phenomenon, whereas eserine inhibited the far red-induced release from glass. THESE AND OTHER DATA SUPPORT THE CONCLUSION THAT ACETYLCHOLINE FUNCTIONS IN MUNG BEAN ROOTS AS IT DOES IN ANIMAL SYSTEMS: by mediating changes in ion flux across cell membranes. It also seems probable that acetylcholine acts as a local hormone which regulates these phytochrome-mediated phenomena.

Functional significance of isoenzymes in thermal acclimatization. Acetylcholinesterase from trout brain

1. The effects of acclimatization temperature on the catalytic properties of acetylcholinesterase from rainbow-trout brain were examined. 2. Trout brain acetylcholinesterase occurs in two distinct forms. A single ;warm' variant of the enzyme is present after acclimatization to 17 degrees C; a single ;cold' variant appears after acclimatization to 2 degrees C. Both forms are present in fish after acclimatization to an intermediate temperature. 3. The K(m) values of the enzyme variants for acetylcholine are temperature-dependent, the lowest values coinciding with the acclimatization temperature at which each enzyme was induced. 4. It is concluded that the K(m)-temperature relationship is adaptive, and that the critical process during thermal acclimatization, in cases where enzymes show sharp changes in K(m) with temperature, is the synthesis of a new enzyme variant that is better suited for catalysis and control of catalysis under the conditions of the acclimatized state.