The Soluble State

The conventional approach to the understanding of chemical events is to model a system with the reagents (reactants) as isolated participants. On occasion, recognition is made of the presence of a dimer or a hydrate as a functioning member of a chemical interaction (reaction). But these are exceptions. The role of the solvent (e.g. water in a biological reaction) is usually neglected because it is poorly understood (Testa, 1984). 

Upon reflection, it becomes clear that a solute is immersed in a solvent that itself possesses some architecture, a fact particularly true for water (see above). Molecular reactions or interactions do not occur in vacuo but must take place with the solvent as an intimate participant. Within this architecture a molecule in an aqueous or organic solution is not like a 

Under these conditions, aggregates display emergent properties (e.g. the state of being soluble, see above) not seen in the neat state. The soluble state also exhibits emergent properties such as diffusibility, conductivity, partitioning between solvents and interfacial activity (Testa and Kier, 1991). What is lost here are many physical properties which have no meaning in the soluble state, namely properties of the crystal, gas or bulk liquid. 

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The polymerase can occur in either a soluble (hydrophilic) or a granule-bound (hydrophobic) form, depending on prevailing conditions of life. During growth under carbon substrate limitation, the enzyme exists mainly in the soluble state, and after transfer to nutrient-limiting conditions, e.g., ammonium limitation, the granule-associated polymerase appears (for review see [25]). 

Nonetheless, one cannot exclude the probability of a successful combination of these prerequisites (as was the case with poly[(NiPAAm-co-GMA)-g-PEO considered above]) that will allow us to obtain, using the chemical colouring approach, the protein-like HP-copolymers with a dense hydrophobic core wrapped by the hydrophilic shell. Such a shell should be capable of efficiently protecting the temperature-responsive macromolecules against pronounced interchain hydrophobic interactions and precipitation at temperatures significantly higher than those at which the copolymers of the same total monomer composition—but with a non-protein-like primary sequence of comonomer units—are in the soluble state. 

Both these enzymes are commercially available and inexpensive. Probably for this reason, they have almost always been utilized in the soluble state, and in great excess. However, it may be observed in Table III that these enzymes are much more efficient when31 immobilized on PAN. Aldolase requires dihydroxyacetone phosphate as ketonic partner, but will accept each of a wide collection of aldehydes as substrates.32 In all cases, the newly built, vicinal diol has the D-threo configuration (see Scheme 6). 

Stoichiometric quantities of uridine diphosphate glucose were used, in the presence of a transfer enzyme, sucrose synthetase, in the soluble state (extraction given). Coupling with modified D-fructose gave sucroses modified on the D-fructosyl group, on the 1 -3-mmol scale. Thus were prepared l -deoxy-l -fluoro- (59%),98 4 -deoxy-4 -fluoro- (16%), and l -azido-l -deoxy-sucrose (15%).71 6-Deoxy-6-fluoro-D-glucose was isomerized to 6-deoxy-6-fluoro-D-fructose with isomerase, and gave 6 -deoxy-6 -fluoro-sucrose.71... 

The major factors in deciding which temperature to use are the solubility, state of aggregation, and, most importantly, long-term stability of the peptide or protein sample. Thus, there has been a general trend toward decreased sample temperatures in biomolecular NMR studies as the size of protein being studied has increased (see Chapter 9.07). While many early NMR studies of peptides and small proteins were performed above room temperature (30-50 °C), most recent studies of larger proteins have been carried out at lower temperatures (typically 20-25 °C) due to sample instability at higher temperatures. 

Soluble polymers Non-crosslinked, linear polymers are soluble in suitable solvents. In the soluble state, high mobility of the bound catalyst and good mass transport are guaranteed and, therefore, catalytic properties will practically not be affected. However, separation of such catalysts is often problematic and costly since it is done either by ultrafiltration or precipitation. 

The steady state kinetic behavior of such an enzyme membrane reactor is only related to the kinetic behavior of enzymes in the gel or in the soluble state. Unless knowledge of intrinsic enzyme kinetics both in the gel and in the soluble form is available, a steady state analysis is not useful for determining whether gel formation has occurred. 

An effective distinction between enzymes in gel form and enzymes in the soluble state can be achieved by the analysis of the transient behavior of the enzymatic reaction.30 33... 

Adsorption-desorption processes This process is the interconversion of molecular species between the soluble and the surface-confined state. This may be detectable when the two states exhibit a difference in light absorption. The soluble state gives rise to an absorption spectral feature, while the adsorbed... 

Rate measurements on fine amorphous powder and colloids have been made by Doremus et al. (224) and by Friedberg (225). The effects of pH, temperature, and presence of salts were similar to those reported by others. More than 50 years ago, Dienert and Wandenbulcke (226) reported the basic facts that colloidal silica passed into solution as soluble silica, which was detectable colorimetrically with molybdic acid, and that alkalinity and salts were good catalysts for dissolution. They made an observation which apparently has never been followed up. They claimed that when salt is present, the dissolution rate is faster in a quartz container than in platinum and that in the absence of added salt, colloidal silica would pass into the soluble state when heated with water in quartz, but not in platinum. However, pH measurements were not made. 

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