Proteolytic-based method for the identification of human growth hormone.

Human growth hormone (HGH) is a relatively small protein consisting of 191 amino acids and has an average mass of 22,125 amu. The forensic analysis of proteins such as HGH must meet the analytical sufficiency requirements for the laboratory and consists of a binary approach. A suspected sample is analyzed as the whole protein for retention time and mass determination using high performance liquid chromatography equipped with a photodiode array and liquid chromatography mass spectrometry. Further fragmentation of the protein using a proteolytic enzyme adds another dimension to the specificity of the analysis. Porcine trypsin digests proteins in a very predictable manner and yields peptide fragments of the original protein that can be used as a means for fingerprinting the larger biomolecule. In silico, or theoretical, digestion of HGH by trypsin yields 21 peptides ranging in size from 1 to 23 amino acids in length. The larger fragments containing higher numbers of amino acids give more specificity to identifying a protein based on a fragment produced by the digestion of trypsin. Herein, the analysis of HGH using a proteolytic approach is presented that meets the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) recommendations for the identification of unknown substances.

Cyclometalated products of [(COE)(2)RhCl](2) and 1,3-(RSCH(2))(2)C(6)H(4) (R = (t)Bu, (i)Pr) Are Dimeric. Synthesis, molecular structures, and solution dynamics of [mu-ClRh(H)(RSCH(2))(2)C(6)H(3)-2,6](2).

Two tridentate thioether pincer ligands, 1,3-(RSCH(2))(2)C(6)H(4) (R = (t)()Bu, 1a; R = (i)()Pr, 1b) underwent cyclometalation using [(COE)(2)RhCl](2) in air/moisture-free benzene at room temperature. The resultant complexes, [mu-ClRh(H)(RSCH(2))(2)C(6)H(3)-2,6](2) (R = (t)Bu, 2a; R = (i)Pr, 2b) are dimeric both in the solid state and in solution. A battery of variable-temperature one- and two-dimensional (1)H NMR experiments showed conclusively that both complexes undergo dynamic exchange in solution. Exchange between two dimeric diastereomers of 2a in solution occurred via rotation about the Rh-C(ipso) bond. The dynamic exchange of 2b was significantly more complex as an additional exchange mechanism, sulfur inversion, occurred, which resulted in the exchange between several diastereomers in solution.