The tyrocidines are cyclic decapeptide antibiotics produced by specific strains of Bacillus brevis. Enzyme-bound intermediate peptides, including Phe-Pro-, Phe-Pro-Phe-, Phe-Pro-Phe-Phe-, and others, up to the linear decapeptidyl Phe-Pro-Phe-Phe-Asn-Gln-Phe-Val-Orn-Leu-, can be isolated from appropriately constituted mixtures by precipitation with trichloroacetic acid, and then identified on tw...

Aromatic-aromatic interactions between phenylalanine side chains in peptides have been probed by the structure determination in crystals of three peptides: Boc-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe, I; Boc-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe, II; Boc-Aib-Ala-Phe-Aib-Phe-Ala-Val-Aib-OMe, III. X-ray diffraction studies reveal that all three peptides adopt helical conformations in th...

OBJECTIVE The aim of the present study was to examine to what extent maternal and offspring phenylalanine hydroxylase (PAH) genotypes in conjunction with maternal IQ and dietary control during pregnancy are related to cognitive development in offspring of women with phenylketonuria (PKU). METHODS PAH gene mutations were determined in 196 maternal PKU subjects and their offspring. The women we...

In phenylketonuria (PKU), natural protein tolerance is defined as the maximum intake maintaining a blood phenylalanine (Phe) concentration within target therapeutic range. Tolerance affected by several factors, and it may differ throughout person’s lifespan. Data on lifelong Phe/natural are limited mostly reported in studies with low subject numbers. This systematic review aimed to investigate ...

The aim of this work was to evaluate, in vitro, the effect of L-alanine (Ala) on suckling rat brain acetylcholinesterase (AChE) and on eel Electrophorus electricus pure AChE inhibited by L-phenylalanine (Phe) as well as to investigate whether Phe or Ala is a competitive inhibitor or an effector of the enzyme. AChE activity was determined in brain homogenates and in the pure enzyme after 1 h pre...

Phenylketonuria is a common metabolic disorder disease. Those affected appear normal at birth, but without treatment they develop severe psychomotor retardation. Throughout life, they must control their blood levels of phenylalanine (Phe) and consume a diet containing adequate amounts of Phe and tyrosine (Tyr). We have developed a liquid chromatographic/mass spectrometric (LC/MS) method for the...

The proteolytic processing of polyproteins by the 3CL protease of severe acute respiratory syndrome coronavirus is essential for the viral propagation. A series of tripeptide a,b-unsaturated esters and ketomethylene isosteres, including AG7088, are synthesized and assayed to target the 3CL protease. Though AG7088 is inactive (IC50 > 100 lM), the ketomethylene isosteres and tripeptide a,b-unsatu...

The effect of different L-phenylalanine (Phe) concentrations (0.12-12.1 mM) on acetylcholinesterase (AChE), (Na+,K+)-ATPase and Mg2+-ATPase activities was investigated in homogenates of adult rat whole brain and frontal cortex at 37 degrees C. AChE, (Na+,K+)-ATPase and Mg2+-ATPase activities were determined after preincubation with Phe. AChE activity in both tissues showed a decrease up to 18% ...

The l-amino acid ligase RizA from B. subtilis selectively synthesizes dipeptides containing an N-terminal arginine. Many arginyl have salt-taste enhancing properties while Arg-Phe has been found to antihypertensive effect. A total of 21 variants were created by site-directed mutagenesis eight amino acids in the substrate binding pocket. recombinantly produced E. coli and purified affinity chrom...