Stanford Synchrotron Radiation Lightsource

Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorous.  Although these six elements make up biomolecules such as nucleic acids, proteins, and lipids, it is theoretically possible that some other elements in the periodic table could serve similar functions.  In a paper published in Science, Wolfe-Simon et. al., describe a bacterium of the Halomonadaceae family, strain GFAJ-1 which appears to substitute arsenic for phosphorous to sustain its growth.

Nephrogenic systemic fibrosis, or NSF, is a relatively new disease in which the skin becomes hardened, joint movement becomes difficult and, in extreme cases, an excessive and sometimes fatal fibrosis tissue forms around organs. So far, NSF has only been observed in patients with kidney dysfunction who have undergone an MRI that required the injection of gadolinium-based contrast agents (GBCAs). Researchers speculate that the patient's kidneys cannot break down the gadolinium, causing NSF, but until now there has been no direct evidence for such a link.

The life-sustaining element oxygen can’t do its job alone. Specialized enzymes, containing metallic elements including iron, cause O₂to split into two separate oxygen atoms.  In this form, oxygen can react with other biological molecules. The precise mechanism of oxygen activation by iron complexes has long eluded researchers, in part because the reaction—which proceeds through multiple intermediate stages—happens in mere fractions of a second.

Sulfur is essential for all life, but it plays a particularly central role in the metabolism of many anaerobic microorganisms. Prominent among these are the sulfide-oxidizing bacteria that oxidize sulfide (S2-) to sulfate (SO42-). Many of these organisms can store elemental sulfur (S0) in "globules" for use when food is in short supply (Fig. 1). The chemical nature of the sulfur in these globules has been an enigma since they were first described as far back as 1887 (1); all known forms (or allotropes) of elemental sulfur are solid at room temperature, but globule sulfur has been described as "liquid", and it apparently has a low density – 1.3 compared to 2.1 for the common yellow allotrope α-sulfur.

Protein crystallography can routinely determine the 3D structure of protein molecules at near atomic or atomic resolution. The bottleneck of this methodology is to obtain sizable and good quality protein crystals. Overcoming the crystallization difficulty requires the development of the new methodologies. One approach is to use NMR to image protein molecules in solvent. However, it is only applicable primarily to macromolecules in the lower molecular weight range. Another approach under rapid development is single molecule imaging using cryo electron microscopy (cryo-EM).

The combined use of x-ray crystallography and solution small angle x-ray scattering has enabled a research collaboration involving scientists from Boston College and SSRL  to provide structural evidence supporting a 30-year old model accounting for the cooperative binding of ligands to allosteric proteins and enzymes - a function central to physiology and cellular processes.