Your sweet tooth may get a treat that is literally "out of this world," thanks to experiments aboard the Space Shuttle.
A team comprising French and American scientists reports they have crystallized one of the most interesting families of intensely sweet proteins, a natural molecule called thaumatin, isolated from the African Serendipity Berry (Thaumatococcus daniellii).
Using otherwise similar crystallizing conditions, the space crystal showed a nearly 25% larger volume compared to its earth-grown counterparts and yielded nearly twice the crystalline order. Scientists hope to use the space-grown crystals to improve the biological understanding of how these molecules work based on detailed knowledge of their shape and exact atomic positions. According to the study, the visual quality of the space crystals "appeared virtually flawless, with no observable imperfections, striations or anomalies."
The complex and costly management of human diabetes, obesity, and oral health has spawned a widespread search for natural sugar substitutes that are both non-caloric and safe. The calorie-free thaumatin protein, sometimes called nature's "artificial sweetener" was analyzed by scientists from the University of California, Irvine and the Institute for Molecular Biology in Strasbourg, France.
In a control study, the team compared space-grown thaumatin crystals with some previously obtained from on earth in a conventional laboratory. They found that the space crystals provided 30% more real information about the molecule's shape. This moves the investigation closer to revealing the biological function of these complex molecules
According to their report, the space crystals reinforce the conclusion of other reports based on different macromolecules that a microgravity environment provides distinct advantages. In the best of only a few thaumatin crystals grown in microgravity, compared with many more trials conducted on earth, the microgravity grown crystals were consistently and significantly larger, and substantially more defect free. This is the first experiment to produce space crystals by multiple methods, both suggesting the same conclusion: crystals grown in microgravity can be significantly improved in their x-ray diffraction properties when compared with those grown on earth.
The natural proteins as a group are the sweetest compounds ever discovered. The sweet taste - which depends on nearly 100 different sensory receptors on the tongue - can be detected in the presence of thaumatin at concentrations well below one part protein molecule per 100 million parts of water. On a scale in which 0 refers to no sweetness, 1 refers to table sugar or sucrose, then thaumatin is nearly off the scale at 3,000, more than 10 times sweeter than other sugar substitutes like saccharin or aspartame.
Because these kinds of complex sensory-stimulating proteins typically require binding to specific taste receptors, much of their biology remains to be worked out in the kind of studies done on the space shuttle and using modern tools of biological crystallography. Already within the bulk commercialization by biotechnology companies, Tate & Lyle's product, Talin, is marketed from thaumatin. Also, at the Unilever Research Laboratory in The Netherlands, the gene for this sweetener has been cloned into biological production using the microorganisms E. coli and yeast to substitute for the original African shrub.
As a non-caloric sweetener, thaumatin has attracted attention as a candidate for control of obesity, oral health and diabetic management. Thaumatin already is being marketed as a nutritional supplement in blood sugar stabilizers for childhood behavioral problems and the more than 3.5 million sufferers from attention deficit disorder. Among soft drink consumers alone, nearly 20.6 million tons of chemicals are used around the world - nearly 4 kilograms per capita, with a growth of about 20% towards the end of the decade.
Control of diabetes, the most common metabolic disease in the world, largely hinges on managing sugar levels in the bloodstream. According to a recent study published in the Journal of Clinical Endocrinology and Metabolism, one out of every 7 health care dollars, or $105 billion goes to the treatment of diabetes-related complications. Individual diabetics spent an average of $9,493 on health care in 1992, the latest data available, compared with $2,604 for people without diabetes, the study said. The National Institutes of Health proved that nearly 16 million diabetic patients who can potentially maintain blood-sugar levels as close as possible to normal can significantly slow the disease.