Protein problems

Jenkins N. and Curling E.M. (1994), Glycosylation of recombinant proteins problems and prospects, Enzyme Microb. Technol. 16, 354—364. 

There is no doubt that for much of the world population fish are the main source of animal protein. Twenty years ago, it was thought that increasing the world catch would solve the world s animal protein problem. More realistic projections currently show that the stock may not meet the demand, especially in develc ing countries. The thought today is that better management, such as through technological advances, is needed to take the strain off the catch and make better use of fish end-products (16). 

The use of other hosts for HTP cloning, expression, and purification has been much more limited than E. coli, which remains the system of choice for high-level protein production. However, for many mammalian and viral proteins, problems of... 

The contributions of Richard Block to the serum protein problem originated from the hypothesis of Kossel. From recent data on the amino acid composition of the proteins found in animal sera, a formulation is derived which reflects the properties of a continuous system of molecular species originating from a common biosynthetic pathway, as if from mixed polymers of monomeric peptides of lower molecular weight. Indirect evidence of this is found in the amino acid interrelationship, and direct evidence is limited to the isolation of peptides of common composition, whose primary structures are still under investigation. These findings suggest that undifferentiated proteins may be continuous systems rather than discrete molecular species. 

Exciton theory deals with the theory of electronic excitation processes in ordered arrays of absorbers (Kasha, 1959). Applications of exciton theory to protein problems have not been numerous, but some important results, especially on the conformation-dependence of the peptide absorption around 2000 A, will be discussed in the section on peptide-bond absorption. 

Bergh, M.L.E., Hubbard, S.C., and Robbins, P.W. (1988). Glycosylation of heterologously expressed proteins problems and solutions. In Therapeutic Peptides and Proteins Assessing the New Technologies. D.R.Marshak and D.T.Liu, eds. (New York Cold Spring Harbor Laboratories), pp. 59 68. 

Bacillus subitilis Second best studied bacteria Gram positive—no outer membrane—excretes proteins Problem excreting some foreign proteins Makes large amounts and varieties of proteases (degrades proteins rapidly) More difficult to manipulate genetically owing to limited vectors and promoters Instability of plasmids more problematic than E. coli... 

The protein problem, wliich lies at the intersection of many disciplines, is highly complex. Evolution complicates the situation even further. Human design allows for... 

Bentonite treatment is used to prevent protein problems in white wines (Sections 5.6.2 and 5.6.3), but it is also very effective for clarifying red wines and stabilizing colloidal coloring matter. Finally, siliceous earths and polyvinylpolypyrroli-done (PVPP) may also be useful for clarifying certain wines. 

These modern discrete analyzers (Figure 2), typically utilize wet-chemistry with photometry of selective electrodes for the cations sodium and potassium. Dry-film technology using similar measurement principles are a significant minority of clinical analyzers. Each test is delivered as an individual slide, which minimizes infection risks. Either type allows different mixtures of tests within a defined menu to be done on different samples during the same analytical run (discretionary). The protein problem is circumvented by sample dilution and the use of surfactants. 

More recently, direct coupling (hyphenation) of MALLS and RI detectors to flow FFF channel has been used to provide direct, accurate determination of molecular weights, Rg and conformation of polymeric wheat proteins. Problems such as overloading the FFF channel in order to provide sufficient signal for RI/MALLS have been addressed for both asymmetrical " and symmetrical" " FFF. 

The rhodopsin protein problem An all-atom rhodopsin protein was set in a solvated lipid bilayer described via the Chemistry at Harvard Molecular Mechanics (CHARMM) force field. Long-range coulomb interactions were described via the particle-particle mesh. SHAKE constraints were applied to the system for the definitions of the force field and constraints. Further, the model consisted of counter ions with a reduced amount of water the effect was to have a total system with 32,000 atoms that was simulated for 100 time steps. This simulation was performed at a constant pressure and temperature with an LJ force cutoff of 10.0 Angstroms. In this problem, the total number of neighbors per atom was 440 within this force cutoff More information about the benchmark problem can be found at http //lammps.sandia.gOv/bench.html rhodo... 

For a fixed-size problem, the parallel efficiency drops dramatically with an increasing number of cores, because the communication overheads far supersede the actual computation—an observation valid for both the LJ liquid and the rhodopsin protein problems. The parallel efficiency drops to below 10%. The communication time contributes to more than 80% of the total run time. Typically, one would resort to a fixed-size scaling only when the problem size is such that it cannot fit on one core. It is the scaled-size problems that present an interesting aspect for large-scale computations. 

FIGURE 10.7 Parallel efficiency of the scaled rhodopsin protein problem as a function of the number of processors on various parallel computers. The numbers in brackets in the legend represent single processor times for each computer. Data for machines apart from Eka were obtained from the LAMMPS website. 

Because of the low protein content of normal human CSF, it is possible to use single pulse H NMR experiments to obtain biochemical information without recourse to the spin-echo techniques often required for studies on blood and plasma. However, where serious cerebral damage has occurred, or in the presence of an acute infection, spectra may become dominated by broad resonances from proteins. Problems may also arise from protein binding and metal binding of some metabolites, with a consequential broadening of their proton resonances. 

Jenkins N, Curling EM. Glycosylation of recombinant proteins problems and prospects. 

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