Protein chemists

It is likely that any new enzymes isolated by screeners will be quickly and routinely cloned by genetic engineers, and be sequenced and expressed as almost pure proteins. Protein chemists can then evaluate the properties of the new enzyme and determine its three-dimensional stmcture. This vast amount of information allows the protein engineers and their computers to design the enzymes of the future. 

Cells contain thousands of different proteins. A major problem for protein chemists is to purify a chosen protein so that they can study its specific properties in the absence of other proteins. Proteins have been separated and purified on the basis of their two prominent physical properties size and electrical charge. A more direct approach is to employ affinity purification strategies that take advantage of the biological function or similar specific recognition properties of a protein (see Table 5.5 and Chapter Appendix). 

Levinthal s paradox led protein chemists to hypothesize that proteins must fold by specific folding pathways, and many research efforts have been devoted to the search for these pathways. 

Because the denatured state has long been thought to be essentially random and because of the inherent difficulties in defining and interpreting structural data averaged in very complex ways, protein chemists have been slow to take up the structural characterization of denatured proteins. Yet a more complete description of the relatively small amounts of persistent structure they display is not simply of academic interest. There are compelling reasons to pursue structural studies of proteins that are not folded. 

Protein chemists use units of daltons rather than molecular mass although the two are interchangeable. 

Cf., C. Transford and J. Reynolds, Protein chemists bypass the colloid/macromolecule debate, Ambix 46 (1999) 33-51. It is true that some protein chemists had conceived... 

Several instruments have been developed in various laboratories since the late 1970s. Currently, several companies have introduced the capillary electrophoresis commercially (for example Microphoretic Systems, Sunnyvale, California Bio-Rad, Richmond, California Applied Biosystems, Inc., Foster City, California and Beckman Instruments, Inc., Palo Alto, California). Although the instruments have many practical features for the separation and analysis of analytes, several new features need to be incorporated (for routine use) by protein chemists. 

Finally, the dream of every protein chemist is not only to... 

Another aspect of the question as to whether the native state of a protein is an equilibrium one concerns its conditions of synthesis in contrast to the conditions under which it is studied by the protein chemist. As a protein is synthesized, we may envisage it peeling off the ribosomes. Even if it is synthesized under equilibrium conditions, the conformation of the growing chain (which could change as each amino acid is added to it)... 

A reaction worth noting in the context of nitro-group interactions with <-amino functions involves the rapid photolytic breakdown of 2,4-dinitrophenyl derivatives of a-amino acids. The lability of such derivatives in sunlight has long been known to protein chemists who... 

---