FIGURE The glucose carrier switches easily between two shapes. UNFIGURE 11.1. FIGURE (A) The monomeric oxygen-carrying protein myoglobin. Illustration: Irving Geis. Rights owned by Howard Hughes Medical Institute. Reproduction by permission only. (B) Oxygen binding of myoglobin (in red) and hemoglobin (in purple) as oxygen pressure increases. FIGURE A pH change that alters the charge on histidine will alter the balance of forces within a protein. At pH 6, the structure on the right will predominate. FIGURE Phosphorylation changes the charge pattern, and hence the balance of forces within the calcium ATPase, forcing a change of shape. FIGURE Catalysts act by reducing the activation energy (A) of a reaction. UNFIGURE 11.3. FIGURE Definition of v 0, the initial velocity of a chemical reaction. FIGURE v 0 measured in a number of reaction tubes (with [E] constant and always less than [S]) forms a hyperbolic curve when plotted as a function of substrate concentration. UNFIGURE 11.1. FIGURE Aminotransferases use a cofactor that participates in the reaction but ends up unchanged. FIGURE Phosphofructokinase is regulated by the binding of ATP or AMP at a regulatory site that is separate from the active site. Binding of ATP inhibits while binding of AMP activates. FIGURE Control of Cdk1 by cyclin B and by phosphorylation.