Alkaline Phosphatases: Structure, substrate specificity and functional relatedness to other members of a large superfamily of enzymes

Our knowledge of the structure and function of alkaline phosphatases has increased greatly in recent years. The crystal structure of the human placental isozyme has enabled us to probe salient features of the mammalian enzymes that differ from those of the bacterial enzymes. The availability of knockout mice deficient in each of the murine alkaline phosphatase isozymes has also given deep insights into their in vivo role. This has been particularly true for probing the biological role of bone alkaline phosphatase during skeletal mineralization. Due to space constraints this mini-review focuses exclusively on structural and functional features of mammalian alkaline phosphatases as identified by crystallography and probed by site-directed mutagenesis and kinetic analysis. An emphasis is also placed on the substrate specificity of alkaline phosphatases, their catalytic properties as phosphohydrolases as well as phosphodiesterases and their structural and functional relatedness to a large superfamily of enzymes that includes nucleotide pyrophosphatase/phosphodiesterase

Effect of broiler breeder age on pancreas enzymes activity and digestive tract weight of embryos and chicks

A study was carried out to evaluate the effect of broiler breeder age on the development of the digestive tract of embryos and chicks. Fertilized eggs Cobb from 30 and 60 week-old broiler breeder was utilized in this experiment. The results showed that eggs from older (60 weeks of age) broiler breeders were heavier (p = 0.001) than those from younger (30 weeks of age) broiler breeder. In addition, older broiler breeder had larger (p = 0.001) embryos showing a higher yolk sac (p = 0.001) and higher gastrointestinal tract relative weight (p = 0.007) than those from younger broiler breeder. The activities of pancreatic lipase and trypsin enzymes were also higher in embryos from older broiler breeder than those from younger broiler breeder (p = 0.001 and p = 0.002, respectively). Nevertheless, at the seven-day-old chick, no difference was observed in relative weight of gastrointestinal tract or pancreatic lipase and trypsin activities between older and younger broiler breeder age. However chicks from older broiler breeder were heavier than those from younger broiler breeder (p = 0.005). These data suggest that broiler breeder age is important on grower and on the development of the gastrointestinal tract and pancreatic lipase and trypsin activities of embryo. However after one week of hatching the morphophysiological difference disappear.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Intestinal and pancreas enzyme activity of broilers exposed to thermal stress

Thirty-two Hubbard broilers were raised under commercial husbandry to evaluate the effect of temperature exposure (26 and 35ºC) on the activity of digestive enzymes at different ages (23 and 46 days) and different diet energy levels (2,900 and 3,200 kcal ME/kg). Data were analyzed in a 2x2x2 factorial arrangement (energy/temperature/age) in a completely randomized design. Animals were slaughtered after four hours of heat exposure for sampling of an intestinal segment, to extract alkaline phosphatase, and pancreas, to extract amylase, lipase and trypsin. The activity of intestinal alkaline phosphatase was influenced by energy level and animal age. Energy level of diet and environmental temperature interfered on the activity of pancreatic amylase. Lipase activity was affected only by broiler age. There was no effect of treatments on pancreatic trypsin activity. It was concluded that the activity of the pancreatic enzymes can be regulated by different mechanisms under stress conditions induced by heat