study on serum level of zinc in heamodialysis patients

Zinc is one of the important elements necessary for human growth. CNS utilizes zinc for its biological functions. Zinc is one of the important cofactors of many enzymes in the body and about 200 enzymes contain zinc as their integral part of their structure. If for any reason zinc is omitted from the enzyme structure, those enzymes can not catalyze any biological functions. The fluctuation of this trace element in the body is clinically important. The concentration change of this trace element can lead to some overt and unrecognized manifestations in haemodialysis patients. This study is to determine the possible fluctuation of serum level of zinc in haemodialysis patients before and after dialysis, to explain the differences in concentration of such trace element in these patients. This study is a comparative and nonexperimental study which was carried out on 50 haemodialysis patients chosen randomly from the patients referred to the department of haemodialysis in 5[th] Azar hospital in Gorgan university of medical sciences. The concentration of urea, creatinine, zinc of these patients were determined using laboratory kits and spectrophotometry tchnique before and after the dialysis. The findings were analyzed by wilkacson non parameter analytical method. Results of this study indicated that the average concenteration of zinc in haemodialysis patients after dialysis was 135.32 +/- 59.32 microgram / deciliter which markedly increased in comparison to the serum concentration of this trace element before the dialysis which was 78.38 +/- 37.46 microgram / deciliter [p < 0.05]. Uremia, dialysis membrane, contaminations, heavy metals, and the quality of consumed water in the dialysis procedure, all can pave the way for the abnormality of trace element and clinical manifestation in haemodialysis patients. The trace element variation concentrations in human body clinically are very important because the decrease and increase in level of each trace element has its own clinical manifestation. The increased concentration of this trace element leads to toxification accompanied with clinical syndromes such as diarrhea and vomiting. Therefore, it is suggested that before the process of dialysis the level of released zinc from the different part of dialysis machine [such as pipeline, consumed water and dialysis membrane] be determined and on the basis of such information the level of zinc in haemodialysis patients can be replaced by proper nutrition

Circular dichroism studies of the coenzyme environment in the active sites of mutant forms of the beta-subunit in the tryptophan synthase alpha 2 beta 2 complex.

The circular dichroism has been used to evaluate the effect of mutation on the environment of the pyridoxal phosphate coenzyme in the active site of the beta-subunit in the tryptophan synthase alpha 2 beta 2 complex from Salmonella typhimurium. Seven mutant forms of the alpha 2 beta 2-complex with single amino acid replacements at residues 87, 109, 188, 306, and 350 of the beta-subunit have been prepared by site-directed mutagenesis, purified to homogeneity, and characterized by absorption and circular dichroism spectroscopy. Since the wild type and mutant alpha 2 beta 2 complexes all exhibit positive circular dichroism in the coenzyme absorption band, pyridoxal phosphate must bind asymmetrically in the active site of these enzymes. However, the coenzyme may have an altered orientation or active site environment in five of the mutant enzymes that display less intense ellipticity bands. The mutant enzyme in which lysine 87 is replaced by threonine has very weak ellipticity at 400 nm. Since lysine 87 forms a Schiff base with pyridoxal phosphate in the wild type enzyme, our results demonstrate the importance of the Schiff base linkage for rigid or asymmetric binding. Although the mutant enzymes display spectra in the presence of L-serine that differ from that of the wild type enzyme, addition of alpha-glycerol 3-phosphate converts the spectra of two of the mutant enzymes to that of the wild type enzyme. We conclude that this alpha-subunit ligand may produce a conformational change in the alpha-subunit that is transmitted to the mutant beta-subunits and partially corrects conformational alterations in the mutant enzymes.