Proteus vulgaris agglutination by cystic fibrosis sera

The factor in sera of patients with cystic fibrosis (CF) and their parents which agglutinates Proteus vulgaris has characteristics similar to those of IgG antibody to this organism. Sera of patients without CF who have P. vulgaris infections agglutinate the organism similarly. At present there are too many false-positives in a control population for the test to be widely useful for heterozygote identification.

Crystal structure of 1:1 complex of barbital with 1-methylimidazole

The prediction of a strong hydrogen-bonding interaction between barbital and 1-methylimidazole was confirmed. Two crystal complexes were obtained, 1:1 and 2:1, and the X-ray structure was determined for the 1:1 complex, which is monoclinic, space group P21/c, with a = 12.236(3) A, b = 11.332(4) A, c = 12.495(4) A, and beta = 120.67(1) degrees. The structure contains disk-shaped hydrogen-bonded tetramers with two molecules of each kind. There is a short NH...N hydrogen bond (2.82 A) in which barbiturate provides the NH donor.

Structure of the DNA binding cleft of the gene 5 protein from bacteriophage fd

The structure of the gene 5 DNA unwinding protein from bacteriophage fd has been solved to 2.3-A resolution by X-ray diffraction techniques. The molecule contains an extensive cleft region that we have identified as the DNA binding site on the basis of the residues that comprise its surface. The interior of the groove has a rather large number of basic amino acid residues that serve to draw the polynucleotide backbone into the cleft. Arrayed along the external edges of the groove are a number of aromatic amino acid side groups that are in position to stack upon the bases of the DNA and fix it in place. The structure and binding mechanism as we visualize it appear to be fully consistent with evidence provided by physical-chemical studies of the protein in solution.