Molecular crowding

See Activity Coefficients Additivity Principle Biochemical Thermodynamics Chemical Potential Equilibrium Constants Hess s Law Innate Thermodynamic Quantities Molecular Crowding Thermodynamics, Laws of Thermodynamic Cycle Thermodynamic Equations of State... 

One would conclude that / must approximately equal 28 for this process Hofrichter et al found a similar behavior in nucleation of human hemoglobin S (HbS) the apparent reaction order for the nucleation of HbS aggregation was about 32 (See Hemoglogin S Polymerization). Of course, such analyses are not fully justifiable, because one cannot assume ideality in the solution properties at high protein concentrations (See Molecular Crowding). 

Altered thermodynamic activity of proteins in solution arises when unreactive (or inert) macromolecules are added to a solution and occupy more than a few percent of total solution volume. Terms such as unreactive , "background, or inert are used to emphasize that the added protein need not exhibit and direct binding interaction with the protein of interest. Instead, the consequences have more to do with molecular crowding, and approximate theoretical models show that this effect depends on the shapes and sizes of the macromolecules. Thus, biological fluids are anything but ideal or dilute solutions. 

A thermodynamic parameter (dV/dnB)T,F,n g which describes how the volume of component S in a multicomponent system depends on the change in its amount expressed in mol. Hpiland recently summarized the partial molar volumes of numerous biochemical compounds in aqueous solution. See Dalton s Law of Partial Pressures Concentrations Molecular Crowding... 

Excluded volume effects in cytoplasm, MOLECULAR CROWDING Excluding kinetic reaction mechanisms, HALDANE RELATION EXERGONIC EXOCYTOSIS EXOENZYME EXOERGIC Exo-j8-f ru ctosi d ase,... 

INNATE THERMODYNAMIC QUANTITIES MOLECULAR CROWDING THERMODYNAMICS, LAWS OF THERMODYNAMIC CYCLE... 

MOLECULAR CROWDING Molecular diffusion through large pores, DIFFUSION OF MOLECULES INTO A PORE... 

MACRQSCQPIC CQNSTANT MICROSCOPIC CONSTANT MOLECULAR CROWDING SCATCHARD PLOT... 

MODULUS OF ELASTICITY Volume-exclusion effects of added solutes, MOLECULAR CROWDING Volume occupied by atoms in a macromolecule or solid,... 

Molecular Crowding and Excluded Volume Effects Favor Protein Stability... 

These effects of molecular crowding and excluded volume on protein structure can... 

The phenomenon of molecular crowding and the consequent excluded volume effects that arise from crowding raise important issues concerning protein structure and function in vivo. Other things being equal, one would predict that proteins would be more stable within their intracellular milieu than in dilute solutions—strictly because of excluded volume effects. If increased stability leads to reduced rate of function, then in vitro studies of enzymatic activity (kcat values in particular) may be providing a misleading picture of what occurs in the cell. 

Introducing chemical potentials for biochemical substrates needs to be done with caution when considering, for example, molecular crowding and signaling molecules with limited copy numbers (Parsegian et al., 2000). This simple chemical system is for cellular metabolic networks, and concentrations replace activities in ideal solutions. 

---