Chains of amino acids form proteins that help make up the structure of living matter. But they are most important because they comprise enzymes, the catalysts that drive the metabolic machinery of life. All the components of life could be present, but without enzymes nothing would happen other than Second Law degradation.
Amino acids can exist in either right- or left-handed forms (called D- and L-stereoisomers). Approximately a 50:50 mix forms in laboratory amino acid synthesis. That's also what would have occurred (if it ever really did occur) in the little biopoietic broths nestled on the lightning scorched volcanic landscape at the dawn of the materialists' prehistory. But life's proteins are not composed of a mixture of D-(dextro) and L- (levo) amino acid stereoisomers, they are essentially exclusively left-handed (levo, L-). That's one unsolved problem for proponents of spontaneous generation to the origin of life.
Then there is the Levinthal paradox. Proteins are not just strings of amino acids. They have a secondary, tertiary, and quaternary structure that arises as the string twists, turns, and folds upon itself to create a three-dimensional form. This folded, globular-like structure is critical to function. Once the primary amino acid strings are formed—an immense improbability as you will see—biologically viable protein takes on a mind of its own and proceeds to rapidly fold into a three-dimensional shape in a matter of seconds or minutes. This folded globular-like structure is critical because it exposes reactive sites on the surface to permit specific biological functions.
Evolutionists argue that the reason the protein folds in a particular way is because that creates the most stable, most minimally energetic form of the protein. It's like saying that the reason a ball that was once perched at the top of an inclined board is now resting on the ground is because that is the most minimally energetic place for the ball to be. But just as there are almost countless places for the ball to come to rest after it rolls down the board onto the ground, so too can proteins come to rest in almost limitless shapes. That creates a situation of multiple minimums. But only one shape will do. That's the Levinthal paradox. Even a tiny protein of a hundred amino acids has potentially trillions of folded minimally energetic forms.1,2 Nobody knows why just one version of the folded protein appears in living tissue.
The importance of folded protein shape is highlighted by prion diseases (transmissible spongiform encephalopathies), such as mad cow disease, sheep scrapie, chronic wasting disease in deer, Creutzfeldt-Jakob disease, and perhaps Alzheimer's, dementia, Parkinson's, and other neural degenerative conditions in humans. Prions are normal brain proteins but when they simply fold wrong, devastating diseases result.
Similarly, sickle cell anemia occurs when only two of the 574 amino acids in the blood's oxygen-carrying hemoglobin molecule are wrong. Each red blood cell contains about 280 million molecules of hemoglobin and this defect causes the red blood cells to distort and even rupture. Death can result.
There are hundreds of thousands of proteins and other sequenced molecules of specific structure and shape in every cell. Things have to be perfect for health to proceed. Chance does not make for such perfection.
Also consider that an enzyme could go through all the work of assembling its chain of amino acids, fold in a precise three-dimensional way, and then be scuttled if the temperature rises above 118o F. But before it even comes to that inglorious end, enzymes do not know how to assemble and fold without preexistent DNA. Not only do enzymes need DNA, DNA cannot form without enzymes. It's the old, "which came first, the chicken or the egg?" conundrum.
Dead Ends Are Not Evolution
1. Levinthal, C. Are there pathways for protein folding? Estrait du Journal de
Chimie Physique, 65 (1968), 44.
2. Zwanzig, R., et al. Levinthal's paradox. Proceedings of the National
Academy of Sciences of the United States of America. 89 (1992), 20-22.
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