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Biological processes in organised media. | LitMetric

Biological processes in organised media.

C R Biol

Laboratoire des Processus intégratifs cellulaires, faculté des sciences, université de Rouen, 76821 Mont-Saint-Aignan, France.

Published: February 2003

AI Article Synopsis

  • - The study explores the potential of embedding a Michaelis-Menten enzyme in a gel to enable not only basic catalytic processes but also complex transport mechanisms, suggesting it may create the illusion of multiple enzymes being at work or that allosteric behavior is occurring.
  • - Kinetic parameters can vary significantly in a gel compared to a standard aqueous solution, which complicates the interpretation of enzyme data, making it hard to conclude the presence of different mechanisms or allosteric control based solely on curve fitting.
  • - The research indicates that functional asymmetry can lead to uphill transport, which may challenge previous notions of transport systems being structurally symmetrical; also, manipulating systems (like frog skin) can yield insights into biological processes that simpler methods cannot

Article Abstract

Embedding a simple Michaelis-Menten enzyme in a gel slice may allow the catalysis of not only scalar processes but also vectorial ones, including uphill transport of a substrate between two compartments, and may make it seem as if two enzymes or transporters are present or as if an allosterically controlled enzyme/transporter is operating. The values of kinetic parameters of an enzyme in a partially hydrophobic environment are usually different from those actually measured in a homogeneous aqueous solution. This implies that fitting kinetic data (expressed in reciprocal co-ordinates) from in vivo studies of enzymes or transporters to two straight lines or a sigmoidal curve does not prove the existence of two different membrane mechanisms or allosteric control. In the artificial transport systems described here, a functional asymmetry was sufficient to induce uphill transport, therefore, although the active transport systems characterised so far correspond to proteins asymmetrically anchored in a membrane, the past or present existence of structurally symmetrical systems of transport in vivo cannot be excluded. The fact that oscillations can be induced in studies of the maintenance of the electrical potential of frog skin by addition of lithium allowed evaluation of several parameters fundamental to the functioning of the system in vivo (e.g., relative volumes of internal compartments, characteristic times of ionic exchanges between compartments). Hence, under conditions that approach real biological complexity, increasing the complexity of the behaviour of the system may provide information that cannot be obtained by a conventional, reductionist approach.

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Source
http://dx.doi.org/10.1016/s1631-0691(03)00062-3DOI Listing

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