July 31, 2004 | David F. Coppedge

Gymnastic Enzyme Acts Like Logic Gate

An enzyme named vinculin undergoes “drastic” conformational changes, reports William A. Weis in the July 29 issue of Nature.1  Vinculin, with over a thousand amino acid links, is important at membrane junctions for transporting materials in and out of the cell.  It helps cellular “glue” exit the membrane so that neighboring cells can adhere to one another, such as in epithelial tissues.
    Weis reports on recent studies that show vinculin undergoes radical conformational changes during its action.  It will only build the adhesive junction when the necessary components are in place.  Nothing happens unless the participants are ready; “the binding energy of several partners is needed to overcome the thermodynamic and perhaps kinetic barriers to activation,” he says.  “Viewed in this way, vinculin functions as a logical AND gate, in which binding of two partners is required to generate an output, in this case a stable multi-protein complex”.  What’s more, this automatic regulation is essential for its function; it prevents inappropriate assembly if the amount of product is unstable.

1William A. Weis, “Cell biology: How to build a cell junction,” Nature 430, 513 – 515 (29 July 2004); doi:10.1038/430513a.

Logic, logic gates, regulation: this is the language of intelligent design.  Each of the contacts formed during the “radical” conformational changes of this complicated enzyme is finely tuned to its substrates, and finely tuned to the concentration of ingredients in the cell.  And these finely tuned contacts are determined by the specificity of the sequence of amino acids in this protein, each coded in another language—the language of DNA.  At every step, this system only makes sense in the context of intelligent design.
    There is no suggestion in this paper how vinculin’s specificity in adhesive junctions might have evolved.  But in the latest ICR Impact article #374 (August 2004), organic chemist Dr. Charles McCombs provides very good reasons why unguided chemistry will never produce such functional complexity and specificity.  Unguided chemicals will always follow the laws of (1) chemical stability; i.e., whether the components will react at all, (2) chemical reactivity, or how fast reactants will react, and (3) chemical selectivity, or where the components react.  Working through these principles, he shows that amino acids will not join together without help, and even if they did, far more random, useless, nonfunctional polymers with damaging cross-reactions would result.  The resulting chain would always form blindly according to the relative binding energies of the amino acids.
    It takes an organic chemist careful guidance at each step to produce a functional enzyme.  “Evolutionists say that nature is blind, has no goal, and no purpose, and yet precise selection at each step is necessary,” McCombs says.  Chemicals cannot think, plan or organize themselves, he reminds us, yet Darwinians invoke a false logic that unguided processes yielded logical living systems, like this example with vinculin.  The chemist remarks, “Evolutionists just hope you don’t know chemistry!”

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