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C A Reed

Publications and source records attributed to C A Reed.

70 records · Page 4Linked to original sources
PubMed1974

Structure of an iron(II) dioxygen complex; a model for oxygen carrying hemeproteins.

The preliminary structural characterization of a reversible ferrous dioxygen complex is reported. Mono(N-methyl imidazole) (dioxygen) meso-tetra (alpha,alpha,alpha,alpha-o-pivalamidephenyl) porphinatorino(II), [Fe(O(2))-(N-Me imid) (alpha,alpha,alpha,alpha-TpivPP)], 1, isolated from toluene solution, crystallizes in the monoclinic system with four molecules in a unit cell of dimensions a = 18.690 (3), b = 19.514 (3), c = 18.638 (3) A, and beta = 91.00 (1) degrees . R = 0.15 for 841 reflections having F(2) > 3sigma (F(2)). The complex 1 has four pivalamido groups on one side of the porphyrin forming a hydrophobic pocket of 5.4-A depth which encloses coordinated dioxygen. The dioxygen is coordinated "end-on," with a bent Fe-O-O bond. The Fe-O-O plane bisects an N-Fe-N right angle of the equatorial iron porphyrin plane and is four way statistically disordered. In addition there is a crystallographic 2-fold axis through iron, coordinated oxygen, and nitrogen of the axially bound N-methyl imidazole. Thus there are two types of coordinated dioxygen with the Fe-O-O plane either parallel or perpendicular to the trans axial imidazole plane. Corresponding values for the Fe-O-O bond angles are 135-(4) degrees and 137(4) degrees and for the O-O bond lengths are 1.23 (0.08) and 1.26 (0.08) A, with a dihedral angle of 90 degrees between alternative orientations of the Fe-O-O plane. The Fe-O distance is 1.75 (0.02) A and Fe-N (imidazole) is 2.07 (0.02) A, suggesting multiple bond character in the Fe-O moiety. The similarity of the Mössbauer spectrum of the model complex, 1, with oxyhemoglobin indicates that 1 may be a good model for oxygen binding in the oxygen transport hemeproteins.

Heme↗
PubMedDate not supplied

Optimizing recovery of cytomegalovirus in the shell vial culture procedure.

We have investigated three factors that may be related to the recovery of cytomegalovirus (CMV) using the shell vial culture procedure. First, we compared fluorescent-antibody staining of shell vial cultures using a monoclonal antibody to a CMV immediate early antigen at 16 vs 40 hr after inoculation. Of 332 routinely submitted specimens cultured in duplicate and stained at the different times, 25 (7.5%) were positive at 16 hr and 32 (9.6%) were positive at 40 hr. The increased yield was 28%. Second, we analyzed the effect of using duplicate shell vials (both stained at 40 hr) for all routinely submitted CMV cultures. During a 6-month period, 272 (12.5%) of the 2157 cultures processed with duplicate shell vials were positive, including 222 positive in both vials and 50 positive in only one. Assuming that a single-vial setup would have detected 50% of those positive in only one of the two vials, the increased yield attributable to the duplicate vial was estimated at 10% (25/(222 + 25)). Third, we investigated the effects of seeding density and culture age on the shell vial assay. Cell age of greater than 1 day was associated with a decrease in sensitivity both in cultures that were confluent and in those that were subconfluent at the time of inoculation. Incorporating these findings in the routine shell vial culture procedure used in our Clinical Virology Laboratory has resulted in a greater overall detection of CMV in shell vial cultures than in conventional 6-week tube cultures.

Cell Line↗