Crystal structure of an anti-Lewis alpha Fab determined by molecular replacement methods.

The anti-Lewis alpha mouse immunoglobulin CF4C4 (IgGl, k) Fab has been crystallized from 58% saturated ammonium sulfate in space group Pl; unit cell dimensions a = 43.4 A b = 41.7 A, c = 62.0 A, a = 72.7 degrees, beta = 96.6 degrees, gamma = 100.1 degrees. X-ray diffraction data have been measured beyond 3.0 A Bragg spacing. The crystal structure has been determined by molecular replacement methods, using as search models the constant and variable domains of the mouse immunoglobulin McPC603 (IgA, kappa) Fab. The crystallographic residual for the data 5.0 to 4.0 A, is 0.47. The approximate 2-fold axis relating the VL and the VH domains forms an angle of 164 degrees with the 2-fold axis relating the constant domains. The crystal packing is reasonable.

Bacterial contaminants of collected and frozen human milk used in an intensive care nursery.

BACKGROUND: Use of human milk for preterm and high-risk neonates conveys many potential benefits but also poses practical difficulties. This prospective study examined the prevalence and degree of bacterial contamination of human milk used in the intensive care nursery. METHODS: One hundred eight milk samples collected from 40 mothers were tested for contamination. Samples from mothers whose milk showed a high degree of contamination were retested after counseling on collection methods. RESULTS: Only 12.5% of the samples showed no bacterial growth. Of the contaminated samples, 38% contained > 30,000 colony-forming units/ml. The most common contaminants were Staphylococcus epidermidis (82%) and Acinetobacter (9%), but other contaminants were also encountered. CONCLUSIONS: There were not statistically identifiable common characteristics of mothers whose milk showed abundant bacterial contamination. Only 30% of these mothers showed improvement in the degree of contamination after counseling regarding techniques of milk collection.

Analysis of polar organic micropollutants in water with ion chromatography-electrospray mass spectrometry.

The coupling of ion chromatography (IC) with electrospray mass spectrometry (ES-MS) opens new ways for the determination of polar organic micropollutants in water samples. The technique of conductivity suppression has been found to reduce the background signal in the range of about two orders of magnitude leading to a significant increase in sensitivity. In addition, the formation of salt adducts has been avoided. The usefulness of this method was proven on several polar and environmentally relevant micropollutants such as the herbicide glyphosate and its metabolite aminomethylphosphonic acid (AMPA), the chelating agent ethylenediamine tetraacetate (EDTA) and diacetonketogulonic acid (DAG). This present study has shown that IC-ES-MS is a simple, sensitive and quick method for the determination of these polar organic traces in water samples after separation on an anion-exchange column without any derivatization. In this work, several possibilities of applications of IC-ES-MS (with varying conditions) are presented. Analysis of glyphosate, AMPA, DAG and EDTA in ground and surface water has been achieved by IC-ES-MS without additional sample preparation at a concentration level of 1 microgram/l.

Calmodulin, S-100, and crayfish sarcoplasmic calcium-binding protein crystals suitable for X-ray diffraction studies.

We have grown crystals of calmodulin, of S-100, and crayfish sarcoplasmic calcium-binding protein and are now determining their structures by x-ray diffraction. The sarcoplasmic calcium-binding protein crystallizes from 50% 2-methyl-2,4-pentanediol in space group P2(1)2(1)2(1) with unit cell dimensions of 58.9, 68.5, and 116.1 A, and diffracts beyond 3.0 A Bragg spacing. S-100 crystallized from 15% polyethylene glycol 6000 in space group P4(1) with unit cell dimensions of 56.0, 56.0, and 112.8 A, and diffracts beyond 3.0 A. Calmodulin crystallized from 15% polyethylene glycol in space group P2(1) with unit cell dimensions of 61.8, 56.7, and 40.0 A, beta = 92.7 degrees, and diffracts beyond 5.0 A.