RESUMO
Exposure to environmental arsenic is associated with serious of health issues such as cancer, diabetes and developmental delays in infants and children. In human liver, As(III) S-adenosylmethionine methyl transferase (hAS3MT) (EC 2.1.1.137) was proposed to be an detoxification process by methylation of inorganic arsenite into pentavalent methyl MAs(V) and dimethyl arsenite DMAs(V). More recently the first product was shown to be highly toxic and potentially carcinogenic trivalent methylarsenite (MAs(III)). Our studies are designed to elucidate the mechanism of AS3MT and its contribution to arsenic-related diseases. Here, we report the first crystallization and preliminary X-ray diffraction analysis of the human AS3MT enzyme. The crystals belong to the monoclinic P1211 space group with unit cell parameters of a = 135.03 Å, b = 260.44 Å, c = 279.03 Å, α = 90.00°, ß = 93.36°, γ = 90.00°.
RESUMO
OBJECTIVE: To investigate the impact of 30-minute walking exercise at 70% VO2max on tissue plasminogen activator (t-PA) Ag and plasminogen activator inhibitor type 1 (PAI-1) Ag in obese sedentary males. RESEARCH METHODS AND PROCEDURES: A controlled observational study of the effect of a 30-minute acute exercise bout at 70% VO2max on plasma t-PA antigen and PAI-1 antigen in 10 obese sedentary males matched for age, ethnic origin, and smoking status with 10 nonobese sedentary male controls. RESULTS: The obese group remained hypofibrinolytic compared with the nonobese group at all time-points before, during, and after exercise. t-PA increased in both groups with exercise before returning to baseline values 30 minutes after exercise. PAI-1 did not significantly change in either group with exercise but rose significantly 30 minutes after exercise in the obese group. DISCUSSION: The reduction in fibrinolytic potential in the obese group represents an increase in acute thrombotic risk and could account for the increased incidence of exercise-associated myocardial infarction observed in sedentary obese groups.
