Proteins - continued maintenance

General tendencies in the in-vivo elimination of proteins and peptides may often be predicted from their physiological function. Peptides, for example, frequently have hormone activity and usually have short elimination half-lives. This is desirable for a close regulation of their endogenous levels and thus function. In contrast, transport proteins such as albumin or a-1 acid glycoprotein have elimination half-lives of several days or weeks, which enables and ensures the continuous maintenance of necessary concentrations in the bloodstream. 

Various optical detection methods have been used to measure pH in vivo. Fluorescence ratio imaging microscopy using an inverted microscope was used to determine intracellular pH in tumor cells [5], NMR spectroscopy was used to continuously monitor temperature-induced pH changes in fish to study the role of intracellular pH in the maintenance of protein function [27], Additionally, NMR spectroscopy was used to map in-vivo extracellular pH in rat brain gliomas [3], Electron spin resonance (ESR), which is operated at a lower resonance, has been adapted for in-vivo pH measurements because it provides a sufficient RF penetration for deep body organs [28], The non-destructive determination of tissue pH using near-infrared diffuse reflectance spectroscopy (NIRS) has been employed for pH measurements in the muscle during... 

Biomedical research continues to broaden our understanding of the molecular mechanisms underlining both health and disease. Research undertaken since the 1950s has pinpointed a host of proteins produced naturally in the body that have obvious therapeutic applications. Examples include the interferons and interleukins (which regulate the immune response), growth factors, such as erythropoietin (EPO which stimulates red blood cell production), and neurotrophic factors (which regulate the development and maintenance of neural tissue). 

The production of heterologous proteins for therapeutic use requires selection of the producer cell line, based on yield, monoclonality (for proteins), product quality, stability, and absence of contaminants like bacteria, molds, mycoplasmas, and viruses. Progress in the production of biopharmaceuticals by cell culture is due mainly to the use of diploid cells and continuous cell lines, together with the maintenance of cells by cryo-preservation. It is important to guarantee that the expression system chosen is able to generate the product in a consistent and economically feasible way (Levine and Castillo, 1999). 

Mulations in the genes coding for any of the signaling proteins could conceivably result in the constitutive (continual) operation of the signaling pathway and the consequent maintenance of cell growth. 

Nd YAG laser. Although the analyses of proteins within single human erythrocytes and enzyme activity in cancer cells have been demonstrated by using a continuous UV laserhigh costs and maintenance of the laser are problematic. 

In principle, the crystallization of a protein, nucleic acid, or virus (as exemplified in Figure 2.2) is little different than the crystallization of conventional small molecules. Crystallization requires the gradual creation of a supersaturated solution of the macromolecule followed by spontaneous formation of crystal growth centers or nuclei. Once growth has commenced, emphasis shifts to maintenance of virtually invariant conditions so as to sustain continued ordered addition of single molecules, or perhaps ordered aggregates, to surfaces of the developing crystal. 

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