Biological chemistry chromium

Shumilla, A.J., Broderick, J.R., Wang, Y., and Barchowsky, A., Chromium Cr(VI) inhibits the transcriptional activity of nuclear factor B by decreasing the interaction of p65 with cAMP-responsive elementbinding protein, Journal of Biological Chemistry, 274 (51), 36207-36212, 1999. 

Nieboer, E. and A. A. Jusys. 1988. Biologic chemistry of chromium. Pages 21-79 in J.O. Nriagu and E. Nieboer (eds.). Chromium in the Natural and Human Environments. John Wiley, NY. 

Aluminum Inorganic Chemistry Cadmium Inorganic Coordination Chemistry Chromium Biological Relevance Hard Soft Acids and Bases Lead Inorganic Chemistry Mercury Inorganic Coordination Chemistry Mercury Organometallic Chemistry Thallium Inorganic Chemistry. 

S. A. Katz and H. Salem, The Biological and Environmental Chemistry of Chromium, VCH, Weinheim, 1994, 214pp. 

One of the additional assets of EPR in the study of chromium (bio)chemistry is the fact that, besides the Cr(V) state already discussed, the biologically relevant Cr(III) state57 can also be detected readily with this technique. Even EPR spectra of highly unusual Cr(I) complexes58 have been reported, and high-field EPR allows detection of the Cr(II) state that is EPR-silent at conventional microwave frequencies.59 Furthermore, organic radicals that may be formed during the reduction of Cr(VI) to Cr(III) can be detected with EPR. 

The chemistry shown in Scheme 1 represents a novel route to Cr(V) complexes. Such a mechanism may be important in biological environments and potentially involved in complex processes responsible for carcinogenicity of chromium compounds (112). 

Carreras CW, Pieper R, Khosla C (1997) The Chemistry and Biology of Fatty Acid, Polyketide, and Nonribosomal Peptide Biosynthesis. 188 85-126 Ceulemans A (1994) The Doublet States in Chromium (III) Complexes. A Shell-Theoretic View. 171 27-68... 

A redox titration is based on an oxidation-reduction reaction between analyte and titrant. In addition to the many common analytes in chemistry, biology, and environmental and materials science thai can be measured by redox titrations, exotic oxidation states of elements in uncommon materials such as superconductors and laser materials are measured by redox titrations. For example, chromium added to laser crystals to increase their efficiency is found in the common oxidation states +3 and +6, and the unusual +4 state. A redox titration is a good way to unravel the nature of this complex mixture of chromium ions. 

Finally, it should be noted that this chemistry may have biological relevance. Several metalloenzymes are believed to contain more than one metal ion bound at the active site. One relevant example is the glucose tolerance factor (GTF) which is important for the metabolic degradation of glucose (398-401). GTF is a low-molecular-weight protein which contains chromium(III). Its structure is not known, but it has been suggested that the active site contains a dinuclear chromium(III) complex (401). The fact that hydroxo-bridged dinuclear chromium(III) complexes exhibit reactions which are often very fast compared with those observed for the parent mononuclear species seems to support such a proposal. 

Kaiz. S.A., and H. Salem the Biological and Bmimamemal Chemistry nf Chromium. John Wiley Sl Sons. Inc.. New York. NY. 1994. 

Beyersmann D, Koster A, Buttner B. 1985. Model reactions of chromium compounds with mammalian and bacterial cells. In MerianE, Fre RW, Hardi W, et al., eds. Carcinogenic and mutagenic metal compounds Environmental and analytical chemistry and biological effects. London, UK Gordon and Breach Science Publishers, 303-310. 

Kumpulainen J. 1984. Chromium. In Vercruysse A, ed. Techniques and instrumentation in analytical chemistry. Vol. 4 Evaluation of analytical methods in biological systems. Part B Hazardous metals in human toxicology. Amsterdam, The Netherlands Elsevier Science Publishers, 253-277. 

Pyridinium chlorochromate, described as a safe, stable, and readily prepared alternative to the chromium trioxide-pyridine complex, is a convenient oxidant for primary and secondary alcohols84 and should find use in steroid chemistry. Dimethyl sulphide ditriflate , prepared from DMSO and trifluoromethanesulphonic anhydride at —78°C, has been used to oxidize 3-hydroxy-steroids.85 The biological... 

A special highlight of this chemistry is the possibility to construct compounds with two adjacent - C-labeled carbon atoms [17], which are of great interest for the investigation of biological systems by means of H NMR spectroscopic methods. For this purpose, the starting complexes (i.e. 36) are prepared from C-labelled chromium hexacarbonyl (Scheme 11). 

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