171 s. : il.
- Conspectus
- Fyziologie člověka a srovnávací fyziologie
- NML Fields
- fyziologie
Gating charges in voltage-sensing domains (VSD) of voltage-sensitive ion channels and enzymes are carried on arginine side chains rather than lysine. This arginine preference may result from the unique hydration properties of the side chain guanidinium group which facilitates its movement through a hydrophobic plug that seals the center of the VSD, as suggested by molecular dynamics simulations. To test for side chain interactions implicit in this model we inspected interactions of the side chains of arginine and lysine with each of the 19 non-glycine amino acids in proteins in the protein data bank. The arginine guanidinium interacts with non-polar aromatic and aliphatic side chains above and below the guanidinium plane while hydrogen bonding with polar side chains is restricted to in-plane positions. In contrast, non-polar side chains interact largely with the aliphatic part of the lysine side chain. The hydration properties of arginine and lysine are strongly reflected in their respective interactions with non-polar and polar side chains as observed in protein structures and in molecular dynamics simulations, and likely underlie the preference for arginine as a mobile charge carrier in VSD.
- MeSH
- Arginine chemistry MeSH
- Databases, Protein MeSH
- ERG1 Potassium Channel chemistry MeSH
- Ion Channel Gating MeSH
- Guanidine chemistry MeSH
- Hydrophobic and Hydrophilic Interactions MeSH
- Humans MeSH
- Lysine chemistry MeSH
- Protein Isoforms chemistry MeSH
- Amino Acid Sequence MeSH
- Molecular Dynamics Simulation * MeSH
- Static Electricity MeSH
- Structural Homology, Protein MeSH
- Water chemistry MeSH
- Hydrogen Bonding MeSH
- Structure-Activity Relationship MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Adults of warm- and cold-acclimated tropical cockroaches, Nauphoeta cinerea were exposed to low temperatures of 0 or 5 degrees C for various time intervals (hours to days). Development of chilling-injury (defects in crawling and uncoordinated movements) and mortality during the exposure were assessed and correlated with the changes in concentrations of metal ions (Na(+), K(+) and Mg(2+)) in the haemolymph and coxal muscle tissue. Warm-acclimated insects entered chill-coma at both low temperatures. In their haemolymph, the [Na(+)] and [Mg(2+)] linearly decreased and [K(+)] increased with the increasing time of exposure. The rate of concentration changes was higher at 0 than at 5 degrees C. The concentration changes resulted in gradually dissipating equilibrium potentials across the muscle cell membranes. For instance, E(K) decreased from -49.8 to -20.7 mV during 7 days at 5 degrees C. Such a disturbance of ion homeostasis was paralleled by the gradual development of chilling-injury and mortality. Most of the cockroaches showed chilling-injury when the molar ratio of [Na(+)]/[K(+)] in their haemolymph decreased from an initial of 4.4 to 2.1-2.5. In contrast, the cold-acclimated cockroaches did not enter chill-coma. They maintained constant concentrations of ions in their haemolymph, constant equilibrium potentials across muscle cell membranes and the development of chilling-injury was significantly suppressed at 5 degrees C for 7 days.
- MeSH
- Chemical Phenomena * drug effects MeSH
- Electroencephalography methods utilization MeSH
- Infusions, Spinal methods utilization MeSH
- Animal Experimentation MeSH
- Extracellular Space physiology chemistry metabolism MeSH
- Blood-Brain Barrier physiology chemistry MeSH
- Intracellular Space physiology chemistry metabolism MeSH
- Ion Exchange * MeSH
- Catheters MeSH
- Cerebral Cortex * enzymology chemistry metabolism MeSH
- Permeability MeSH
- Rats, Wistar MeSH
- Statistics as Topic MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
