Allosteric regulation, structural

Freire, E. (2000). Can allosteric regulation be predicted from structure Proc. Natl. Acad. Sci. U.S.A. 97 11680-11682. 

The influence of pH on the affinity of Hb for oxygen known as the Bohr-effect indicates that protons retain the allosteric regulation of oxygen transport. It is also an indirect confirmation of the ability of Hb and Im Hb for transporting carbon dioxide. The values of the Bohr-effect d log P50/d pH for Hb and Im Hb are close to each other in the pH range 7.1-7.4. It is possible that the effect of the micro-environment of carboxylic CP on immobilized Hb and its polyfunctional interaction represents the interaction between Hb and the structural elements inside the red cell [99]. 

The existence of two distinct functions within the one membrane protein raises a number of interesting questions about transporter functions, such as what is the relative importance of the two functions Can they be allosterically regulated under physiological conditions or manipulated by pharmacological methods What is the structural basis for the dual functions In the next section, we shall attempt to address some of these issues and also to present some of the current understanding of the structural basis for these functional states. 

Structural Basis of Allosteric Regulation on the Example of Phosphofructokinase... 

Based on high resolution crystal structures, detailed understanding of the molecular principles of allosteric regulation for several enzyme systems could be gleamed. One of the best studied examples is that of phosphofructokinase from Bac. stearothermophilus (Schirmer and Evans, 1990). 

Hall JM, McDonnell DP, Korach KS Allosteric regulation of estrogen receptor structure, function, and co-activator recruitment by different estrogen response elements. Mol Endocrinol 2002 16 469. [PMID 11875105]... 

Allosteric Regulation Allows an Enzyme to Be Controlled Rapidly by Materials that Are Structurally Unrelated to the Substrate... 

Allosteric effectors are inhibitors or activators that bind to enzymes at sites distinct from the active sites. Allosteric regulation allows cells to adjust enzyme activities rapidly and reversibly in response to changes in the concentrations of substances that are structurally unrelated to the substrates or products. The initial steps in a biosynthetic pathway commonly are inhibited by the end products of the pathway, and numerous enzymes are regulated by ATP, ADP, or AMP. 

In conclusion, it should be pointed out that in marked contrast to the very extensive studies on rabbit muscle phosphorylase, little attention has been paid to enzymes from other sources. However, primary structures of plant phosphorylases have now been determined and bacterial expression systems for the plant enzymes have also been made available as reviewed in this article. We hope that future studies on the structure and function of plant phosphorylases without allosteric regulation and comparison with those of the highly regulated animal enzyme will provide valuable information on this interesting group of enzymes, phosphorylases. 

Hazes B et al (1993) Crystal structure of deoxygenated Limulus polyphemus subunit II hemo-cyanin at 2.18 A resolution clues for a mechanism for allosteric regulation. Protein Sci 2 597-619 PDBID lNOL... 

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