Picturing an enzyme that helps DNA unwind.For a cell to copy, repair, or read its genes, enzymes called helicases must pry apart the two joined strands that form the twisting, ladderlike structure of DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. . Investigators trying to understand how helicases unwind the DNA double helix double helix n. The coiled structure of a double-stranded DNA molecule in which strands linked by hydrogen bonds form a spiral configuration. Also called DNA helix, Watson-Crick helix. can now study an atomic-resolution picture of one such enzyme. In the Oct. 15 CELL, Tom Ellenberger of Harvard Medical School Harvard Medical School (HMS) is one of the graduate schools of Harvard University. It is a prestigious American medical school located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts. in Boston and his colleagues report determining the starlike structure of a viral helicase by shooting X rays through a crystallized crys·tal·lize also crys·tal·ize v. crys·tal·lized also crys·tal·ized, crys·tal·liz·ing also crys·tal·iz·ing, crys·tal·liz·es also crys·tal·iz·es v.tr. 1. version of the enzyme. Investigators hope that such images will provide a better understanding of how a helicase threads one of the DNA strands through its center and then speeds along the molecule. Mutations in the genes for human helicases can cause people to develop cancer or suffer aspects of premature aging, the researchers note. |
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