Cyclo(phenylalanine-proline) is produced by various organisms such as animals, plants, bacteria and fungi. It has diverse biological functions including anti-fungal activity, anti-bacterial activity and molecular signalling. However, a few studies have demonstrated the effect of cyclo(phenylalanine-proline) on the mammalian cellular processes, such as cell growth and apoptosis. In this study, w...

A sensitive method was developed for determining the phenylalanine hydroxylase activity of crude tissue preparations in the presence of optimum concentrations of the 6,7-dimethyl-5,6,7,8-tetrahydropterin cofactor (with ascorbate or dithiothreitol to maintain its reduced state) and substrate. Tissue distribution studies showed that, in addition to the liver, the kidney also contains significant ...

Increasing the plasma phenylalanine concentration to levels as high as 0.560-0.870 mM (over ten times normal levels) had no detectable effect on the rate of brain protein synthesis in adult rats. The average rates for 7-week-old rats were: valine, 0.58 +/- 0.05%/h, phenylalanine, 0.59 +/- 0.06%/h, and tyrosine, 0.60 +/- 0.09%/h, or 0.59 +/- 0.06%/h overall. Synthesis rates calculated on the bas...

Phenylketonuria (PKU) is the inability to convert phenylalanine into tyrosine, causing toxic effects to the central nervous system. Traditionally, in the treatment of PKU, breastfeeding is replaced by formula milk. This study verified the effects of breastfeeding as a source of phenylalanine on the development of children with PKU. Participants were ten infants with PKU who started treatment wi...

The transport characteristics of the placenta, which favour higher phenylalanine concentrations in the fetus than in the mother, and regression data of head circumference at birth against phenylalanine concentration at conception in maternal phenylketonuria (PKU), suggest that treatment of maternal PKU should ideally aim to maintain plasma phenylalanine concentration within the normal range thr...

A method was developed to study the unsupplemented phenylalanine hydroxylase system in rat liver slices. All of the components of the systemtetrahydrobiopterin, dihydropteridine reductase, and the hydroxylase itself-are present under conditions which should be representative of the actual physiological state of the animal. The properties of the system in liver slices have been compared to those...

A method was developed to study the unsupplemented phenylalanine hydroxylase system in rat liver slices. All of the components of the systemtetrahydrobiopterin, dihydropteridine reductase, and the hydroxylase itself-are present under conditions which should be representative of the actual physiological state of the animal. The properties of the system in liver slices have been compared to those...

We evaluated the effects of phenylalanine on reproductive performance and teratogenesis in mice, as well as we assessed its protective effect in mice treated with an acute dose of cyclophosphamide. Animals were divided into 6 experimental groups (females N = 15/group, males N = 5/group): G1, the negative control group, phosphate-buffered saline; G2, the positive control group, 35 mg cyclophosph...

Homology-based modeling of phenylalanine dehydrogenases (PheDHs) from various sources, using the structures of homologous enzymes Clostridium symbiosum glutamate dehydrogenase and Bacillus sphaericus leucine dehydrogenase as a guide, revealed that an asparagine residue at position 145 of B. sphaericus PheDH was replaced by valine or alanine in PheDHs from other sources. This difference was prop...