Protein configurations

In addition to effects on biochemical reactions, the inhibitors may influence the permeability of the various cellular membranes and through physical and chemical effects may alter the structure of other subcellular structures such as proteins, nucleic acid, and spindle fibers. Unfortunately, few definite examples can be listed. The action of colchicine and podophyllin in interfering with cell division is well known. The effect of various lactones (coumarin, parasorbic acid, and protoanemonin) on mitotic activity was discussed above. Disturbances to cytoplasmic and vacuolar structure, and the morphology of mitochondria imposed by protoanemonin, were also mentioned. Interference with protein configuration and loss of biological activity was attributed to incorporation of azetidine-2-carboxylic acid into mung bean protein in place of proline. 

MD simulations with either protein or water constrained at the instant of photoexcitation were performed for both isomer 1 and isomer 2. For isomer 1, because surface water relaxation dominates the slow component of the total Stokes shift, in Fig. 44a we show the result of simulations of isomer 1 with an ensemble of frozen protein configurations to examine the role of protein fluctuations. Clearly the long component of indole-water interactions disappears when the protein is constrained. This result shows that without protein fluctuations, indole-water relaxation over tens of picoseconds does not occur. Thus, although surface hydrating water molecules seem to drive the global solvation and, from the dynamics of the protein and water contributions, are apparently responsible for the slowest component of the solvation Stokes shift for isomer 1 (Fig. 42), local protein fluctuations are still required to facilitate this rearrangement process. When the protein is frozen, the ultrafast... 

Protein denaturation occurs when the protein configuration is changed by the destruction of the secondary and tertiary structures (reduced to the primary structure). Common denaturing agents are alcohol, heat, and heavy metal salts. 

Which of the schematic drawings of protein configuration shown in the figure below represents the conformation of tropocollagen ... 

Glutaraldehyde crosslinks proteins and may alter protein configuration and mask epitopes. Because of its cross-linking properties, penetration of reagents may be impaired. For immunocytochemistry, it is usually used in low concentration in combination with formaldehyde. 

Changes in protein configuration Changes in protein surface charges Interactions between ingredients Competition at oil or air interfaces... 

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