Metalloenzyme active

Fig. 19. The carboxylate-histidine-zinc triad appears in the active site of carboxypeptidase A as Asp-142-His-69—and this interaction may contribute to zinc affinity in the metalloenzyme active site. Atomic coordinates were retrieved from the structure of the native enzyme (Rees et al, 1983) deposited in the Brookhaven Protein Data Bank.

Moreover, zinc is also known for its antioxidant properties. These appear to be independent of zinc metalloenzyme activity, but are based on protecting sulfhydryl groups or antagonizing redox-active transition metals that cause the site-specific formation of free radicals . 

Modeling Phenoxyl Radical Metalloenzyme Active Sites... 

Heteroleptic (see Heteroleptic Compound) alkylzinc thiolate and selenolate componnds present two major interests they can be nsed as models for metalloenzyme activity and as precursors for the formation of binary metal snlfides and selenides. " Furthermore, these compounds tend to... 

Reductions of metalloenzyme activity induced by the deficiency may be partially or whoUy restored by effective treatment. Reversal of hematological and immune function laboratory abnormahties can also be used, as can hormonal changes induced by the deficiency. 

Complexes of N-heterocycles as models of metalloenzyme active sites 86ACR363. 

A comprehensive nutrition assessment must include an evaluation of possible trace element, vitamin, and essential fatty acid deficiencies. Because of their key role in metabolic processes (as coenzymes and cofactors), a deficiency of any of these nutrients may result in altered metabolism and cell dysfunction, and may interfere with metabolic processes necessary for nutritional repletion. The evaluation of single-nutrient-deficiency states includes an accurate history to identify symptoms and risk factors that may indicate deficiency or predispose the patient to developing a deficiency state. A focused physical examination for signs of deficiencies and biochemical assessment to confirm a suspected diagnosis also should be done. Ideally, biochemical assessment would be based on the nutrient s function (e.g., metalloenzyme activity) rather than simply measuring the nutrient s serum concentration. Unfortunately, few practical methods to assess micronutrient function are available currently, and most assays measure serum concentrations of the individual nutrient. 

Goldberg, D. P. Lippard, S. J. Modeling Phenoxyl Radical Metalloenzyme Active Sites. In Mechanistic Bioinorganic Chemistry, Thorp, H. H. Pecoraro, V. L., Eds., American Chemical Society Washington, D.C., 1995 Vol. 246,... 

Y. Rondelez, M.-N. Rager, A. Duprat, O. Reinaud, Calix[6]arene-based cuprous funnel complexes a mimic for the substrate access channel to metalloenzyme active sites, J. Am. Chem. Soc., 2002, 124, 1334-1340. 

Potentially acting between these extremes are synthetic metal complexes that mimic the metalloenzyme active sites and catalyze reactions imder relatively mild conditions. 

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