Find solution
Why do some enzymes exhibit faster than diffusion kinetics?

Why do some enzymes exhibit faster-than-diffusion kinetics?

  • Answer:

    There are two schools of thought regarding overcoming diffusion limited kinetics. The first is that given the enzyme's ability to interact with other substances inside the cell, the enzymes and substrates can move around faster than what their diffusion coefficient would imply. The classical model system is the observations of anomalous superdiffusion of the LacI protein inside a cell. [1][2] The hypothesis is that the LacI protein interacts with DNA and exhibits 1-D diffusion by "sliding" through the strand. Furthermore, it will also exhibit "jumps" to a different DNA strand The second explanation for faster-than-diffusion kinetics is with substrate "channeling". For large protein complexes like polyketides synthases, substrates can be trapped inside the protein and passed from module to module. The common analogy would be an assembly line. Each part is moved to the next operator for its "reaction" and gets pushes by the next incoming part. Contrast that with an open system where you would need to wait for the substrate and the enzyme to meet. Wikipedia also seems to have a few other ideas http://en.wikipedia.org/wiki/Catalytically_perfect_enzyme [1] http://pre.aps.org/abstract/PRE/v83/i2/e021907 [2] http://www.sciencemag.org/content/336/6088/1595.short

Christopher VanLang at Quora Visit the source

Was this solution helpful to you?

Other answers

That's a very interesting question. Recently I attended a seminar at Duke University featuring Professor James Ferrell. http://www.stanford.edu/group/ferrelllab/ He presented a wealth of in vitro and in vivo experiments suggesting this phenomena was due in large part to the pre-distribution of those molecules and the rate of active and inactive state mixing at the boundary between these states. Put more simply, the activation "wave" propagates faster than the rate of diffusion, but only in settings where the initial state molecule is predistributed. Keep an eye on his labs publications, I'm sure they will publish on it soon! EDIT: After reading the answer given by Chris VanLang I realized that the question could be interpreted in two ways- kinetics of motion or kinetics of action. I was answering with respect to kinetics of action. Chris's answer neatly describes the faster-than-diffusion movement theories. There is also evidence for active "flow" in cytoplasmic fluid that can carry particles. See speckle microscopy by Claire Waterman and others for views of that.

Justin English

Related Q & A:

Just Added Q & A:

Find solution

For every problem there is a solution! Proved by Solucija.

  • Got an issue and looking for advice?

  • Ask Solucija to search every corner of the Web for help.

  • Get workable solutions and helpful tips in a moment.

Just ask Solucija about an issue you face and immediately get a list of ready solutions, answers and tips from other Internet users. We always provide the most suitable and complete answer to your question at the top, along with a few good alternatives below.