RESUMEN
The heat inactivation of esterases in human and rabbit serum was followed at 50 and 55 degrees C by measuring the decrease of activity with paraoxon, phenylacetate and beta-naphthylacetate as substrates. The rate of inactivation measured with the three substrates was slightly, but significantly different, indicating that the substrates are hydrolysed by different enzymes.
Asunto(s)
Hidrolasas de Éster Carboxílico/sangre , Monoéster Fosfórico Hidrolasas/sangre , Animales , Arildialquilfosfatasa , Interacciones Farmacológicas , Activación Enzimática , Estabilidad de Enzimas , Calor , Humanos , Hidrólisis , Cinética , Ácidos Naftalenoacéticos/sangre , Paraoxon/sangre , Fenilacetatos/sangre , ConejosRESUMEN
In patients with hyperlipaemia, serum paraoxonase activities were polymodally distributed with 75% individuals in the low activity mode. In the same patients the distribution of serum cholinesterase activities was unimodal, but asymmetrical. Patients with impaired glucose tolerance or non-insulin-dependent diabetes mellitus had slightly higher cholinesterase activities than patients with hyperlipaemia only.
Asunto(s)
Colinesterasas/sangre , Enfermedades Metabólicas/enzimología , Monoéster Fosfórico Hidrolasas/sangre , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Arildialquilfosfatasa , Glucemia/metabolismo , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/enzimología , Femenino , Prueba de Tolerancia a la Glucosa , Humanos , Hiperlipidemias/sangre , Hiperlipidemias/enzimología , Masculino , Enfermedades Metabólicas/sangre , Persona de Mediana EdadRESUMEN
The hydrolysis of paraoxon (POX), phenylacetate (PA) and beta-naphthylacetate (BNA) was studied in human serum. Based upon correlations between enzyme activities, upon reversible inhibition by EDTA and upon progressive inhibition by iso-OMPA, tabun, eserine and bis-4 nitrophenylphosphate, the following conclusions were drawn about the number and specificity of enzymes involved in the hydrolysis. Two paraxonases hydrolyse paraoxon: one sensitive and the other insensitive to EDTA. The EDTA-sensitive paraoxonase also hydrolysed BNA. The EDTA-insensitive hydrolysis of BNA and PA was attributed to a serine esterase. The EDTA-sensitive hydrolysis of PA is probably due to more than one enzyme, which might be an arylesterase and a carboxylesterase.