Amino Acids

Scientists examining ancient rocks have detected organic molecules that they believe could only have been deposited when an extraterrestrial object, probably a comet, crashed into the Earth 65 million years ago. Some researchers say the finding lends powerful support to the hotly debated theory that a cosmic collision threw up a worldwide dust cloud that hampered photosynthesis and set off a mass extinction of dinosaurs and many other animals and...

Dust from disintegrating comets, rich in the molecular building blocks of life, may have rained onto Earth in the distant past, providing a relatively gentle way for such chemicals to reach the surface without being burned up, it was reported last week. How such molecules could have survived the fiery heat of atmospheric entry to reach Earth's surface has been a major stumbling block for those who believe chemicals formed in deep space may have played a role in the origins of life.

Where's the beef? According to the U. S. Department of Agriculture, it's locked in a small molecule that gives meat its natural beefy flavor. The molecule, recently discovered in fresh beef, could improve the flavor of frozen foods, soups, airline meals and a broad variety of other inexpensive foods, USDA animal physiologist Arthur Spanier said here Tuesday at a meeting of the American Chemical Society. "It could make a chuck steak taste like a T-bone," he said.

Researchers have identified what they say is a rare but potentially treatable form of autism. It stems from a gene that controls the breakdown of certain proteins, known as branched chained amino acids. The proteins are important in brain chemistry and must be gotten from food, since the body can't produce them. In most people, the gene slows down the metabolism of the proteins to maintain an available supply in the blood plasma. But certain mutations in the gene deactivate it, so the proteins get broken down too rapidly.

A vegetarian diet may be higher in fat than those containing meat if not carefully designed, warns the California Dietetic Assn. (CDA), Los Angeles District. "A good vegetarian diet--one that provides all nine of the essential amino acids making up complete proteins--is based on the nutrient-based food group system consisting of milk, meat or meat alternates, vegetables and fruits and breads and cereals," said Rita Storey, RD, president of CDA.

The germs have rallied--and they show no signs of retreating. Deadly strains of bacteria have become resistant to even our most state-of-the-art drug defenses. Strains of tuberculosis, for instance, a disease once thought largely eradicated from the developed world, have become resistant to many drugs and, as a result, death rates are on the rise. Even as new antibiotics are introduced, bacteria develops ways to thwart them.

Reporting from Las Vegas — Juan Manuel Marquez, 38, has ached for this third fight against Manny Pacquiao since his 2008 split-decision defeat by one point. Marquez later boarded a flight to the Philippines, begging for another shot at Pacquaio. He watched bitterly as Pacquiao's purses skyrocketed in follow-up victories while Marquez was passed over. On Saturday, Marquez gets his long-awaited shot at Pacquaio, and he has also drawn some scrutiny over how badly he wants to win. At a news conference Wednesday, Marquez thanked a man who spent 11 weeks in training camp as his strength and conditioning coach: Angel "Memo" Heredia.

Dear Dr. Blonz: Many brands of canned tuna have hydrolyzed casein, hydrolyzed soy protein and vegetable broth listed in addition to the expected ingredients. Why are they added? Are these hydrolyzed ingredients as unhealthy as hydrolyzed fats? --K.B. Springfield, N.J. Dear K.B.: Similar to other proteins, soy protein and casein (the major protein found in milk) are made up of amino acids.

Pssst , wanna launch a multibillion-dollar industry and maybe win a Nobel Prize in the process? Then I have just two words for you: Protein engineering. You've all heard of genetic engineering and the biotechnology industry it spawned. Well, protein engineering takes it all down a level; it's the stuff that genes are made of. If you can play with proteins, you're playing with the molecules that matter. Proteins are the real building blocks of life.

Microcosmos: Four Billion Years of Evolution From Our Microbial Ancestors by Lynn Margulis and Dorion Sagan (Summit: $17.95) The story of life on Earth is usually told like this: First there was the primordial soup, which sloshed around for a while getting zapped by lightning and whatnot, creating amino acids, the building blocks of proteins. These proteins eventually got together as DNA, which in turn formed cells.