The crystal structure of AdhP, a recombinantly expressed alcohol dehydrogenase from Escherichia coli K-12 (substrain MG1655), was determined to 2.01 Å resolution. The structure, which was solved using molecular replacement, also included the structural and catalytic zinc ions and the cofactor nicotinamide adenine dinucleotide (NAD). The crystals belonged to space group P2 1 , with unit-cell parameters a = 68.18, b = 118.92, c = 97.87 Å , = 106.41. The final R factor and R free were 0.138 and 0.184, respectively. The structure of the active site of AdhP suggested a number of residues that may participate in a proton relay, and the overall structure of AdhP, including the coordination to structural and active-site zinc ions, is similar to those of other tetrameric alcohol dehydrogenase enzymes.
A method to purify genomic DNA from Escherichia coli is presented. The method is an amalgam of published methods but has been modified and optimized for use in the undergraduate biochemistry laboratory. Specifically, the method uses Tide Free 2× Ultra laundry detergent, which contains unspecified proteases and lipases, n-butanol, 2-propanol, ethanol, and ribonuclease A (or 8 mM sodium hydroxide), and requires a minimum of specialty equipment. Because a number of the required reagents are readily attainable from retail stores, the cost is low enough to allow each student to prepare a sample of purified genomic DNA, even in large laboratory classes. By following the protocol, students are able to purify genomic DNA and use this genomic DNA as a template for a polymerase chain reaction in one 3-h laboratory period.
Intestinal obstruction rarely occurs after uncomplicated vaginal deliveries. Here, we present a case of a multiparous woman with a history of prior appendectomy presenting with generalized, nonspecific abdominal pain that was out of proportion to exam findings. Initial abdominal X-ray was nonspecific, and subsequent computed tomography (CT) abdomen showed closed small bowel obstruction requiring surgical repair. We present a case of intestinal obstruction occurring within 24 hours of uncomplicated vaginal delivery with a risk factor of a prior appendectomy surgery and the use of CT abdomen and pelvis to expedite diagnose.
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