Introd u ction Clinical chemistry, for decades restricted to a limited number of chemical tests, has, in recent years, through an increasing awareness of the value of the laboratory investigation of disease, and the introduc­ tion of automation and sophisticated instru­ mentation, expanded its field of operations to include a bewildering variety of tests. Advances in biochemical knowledge have ...

Pumpkins were treated by spraying the leaves in the flowering period with a water solution containing 1.5 mg Se per liter in the form of Na2SeO4. The average total selenium content of seeds was found to be 0.19 microg g(-1) in nontreated pumpkins and 1.1 microg g(-1) in exposed ones. For speciation analysis, enzymatic hydrolysis with different amounts of Protease XIV was carried out. Under opti...

The role of S-adenosyl-n-methionine as a methyl donor has been investigated in mammalian systems (1) and in microbial metabolism (2-4). In addition, the compound is involved in the formation of spermidine from putrescine (5). Information concerning the stability of S-adenosylmethionine in various enzymatic systems is a necessary prerequisite for studies concerning its role in group transfer. In...

The retinoid (visual) cycle is a complex enzymatic pathway essential for regeneration of the visual chromophore, 11-cis-retinal, a component of rhodopsin that undergoes activation by light in vertebrate eyes. Pathogenic mutations within genes encoding proteins involved in the retinoid cycle lead to abnormalities in retinoid homeostasis and numerous congenital blinding diseases of humans. Thus, ...