Proteins resolution problems

Water plays a critical role in the function of the enzyme, as it provides the medium for proton translocation [12], Recent high-resolution structural data indicate that there is plenty of water inside the protein. The problem is that most important dynamic water molecules that carry protons are not seen in the x-ray structures. Here, computer simulations play the critical role. 

The volatile nature and ultraviolet transparency of the acetonitrlle-TFA eluant appear to make It an attractive candidate for protein SEC. However, we have found that a serious limitation of the system Is the low solubility of proteins of greater than about 15 kDa In 30-45% acetonitrile required for optimum resolution. This poor solubility results in severe protein aggregation problems, apparently limiting the usefulness of this system to peptides and very low molecular weight proteins. 

So far, only proton homonuclear 2D-NOE experiments have been used in a qualitative (or perhaps semiquantitative) sense to obtain structural information from proteins (Kumar et al., 1981 Wuthrich et al., 1982) and, in one case, from poly(C) (Broido and Kearns, 1982). The possibUity exists tliat 2D accordion NMR may also prove useftil if the resolution problem is not too severe (Bodenhausen and Ernst, 1982). 

Although the viscosity of the sample solution may affect the resolution, for practical reasons highly concentrated protein samples will give the best separations in the case of SEC with respect to the process economy. Although the actual loading capacity depends on the separation problem and on the... 

Space resolution of the transducer, in principle, is extremely high. Becanse each BR molecule performs proton pumping, it will be comparable with the protein size (abont 2 mn). In practice, however, it will be limited by the possibility of focusing the light beam. Bnt, in any case, it will be more than in existing transducers, subject to technological problems. 

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