Ionophores, Chemiosmosis, and Chemical Equilibrium

ionophore: a pesomolecular compounds ranging from 500-2000, which have a hydrophobic outer surface which is soluble in lipids, and a hydrophilic interior to which the ion binds. There is little evidence that ionophores are physiological constituents of energy-transducing membranes. Through two mechanisms can function as mobile carriers and as trainers of channels or conduits. The mobile carriers can diffuse through the membrane lipid matrix and catalyze the transport of a few thousand ions per second across the membrane. They can show a high selectivity towards the different ions, heavy work through synthetic membranes, but are affected by the state of membrane fluidity. Example, valinomycin is highly selective for potassium cation. By contrast, the ionophores forming channels show little selectivity for ions, but can be very active and catalyze the transport of more than 10 million ions per second through. One can distinguish the two types of ionophores simply limiting membrane fluidity, or completely solidified. TIONS coupling: mitchell Proposa i q the electronic transport are the Fosforilació associats only by a stream of protons across the membrane. Electrogenic ionic pump empeny fora els cations of the gallbladder, l'convertint metabolic energy in 1 gradient d d potncial electrokim through the mb. Els cations Tornen x 1 altre sist d transport, dissenyat x dock the ionic flux gradient d for the Realització amb treball d kualq useful. If the filtering is excessiva d'ions, the sist not maintain 1 pot pot pot not realitzar electrokim i treball. Relations between d'energia lliure i cnt eq: in 1 proces qualsevol qimic eq quan l's'arribara to the direct reactions vel = q d the d the reverse reactions. X tant d'dfinim the cnt eq the quocient d com les [] dls products in respect als reactius l'eq. Aquest cnt eq 1 is temperature dominad i P d i is independnt them [] inicials d each component. Punt d'eq in the variations d'energia lliure sist dl = 0. Quan es troba sist in the eq, the relations is: Quan Keq is best q 1 the reactions t lloc amb 1 dscens d'energia lliure (is exergonic) Quan Keq is lower q 1 (+) Per mole d aq reactiu is transformi product in 1 mol d 1 i l'altre quan estan a 1 [] 1M is necessari d'energia 1 gives the sist, the reactions are endergonic