Effects of phenylalanine and phenylpyruvate on ATP-ADP hydrolysis by rat blood serum.
The nucleotide (ATP-ADP)/nucleoside (adenosine) ratio in the circulation can modulate the processes of vasoconstriction, vasodilatation and platelet aggregation. The main objective of the present study with rat blood serum was to evaluate the possibility of changes in nucleotide hydrolysis by phenylalanine (Phe) and phenylpyruvate (PP), the levels of which could increase in the circulation of individuals with phenylketonuria. Results demonstrated that Phe in the range 1.0-5.0 mM inhibited the ADP hydrolysis by rat serum. The effect of inhibition by Phe on ATP hydrolysis appeared only at a concentration of 5.0 mM. PP had no significant effect upon nucleotide hydrolysis. Kinetic analysis indicated that the inhibition of ADP and ATP hydrolysis by Phe in rat blood serum is uncompetitive. Conversely, Phe and PP did not affect the hydrolysis of p-nitrophenyl-5'-TMP by rat serum.
Rücker
B
B
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
Oses
J P
JP
Kirst
I B
IB
Berti
S L
SL
Bonan
C D
CD
Battastini
A M O
AM
Sarkis
J J F
JJ
D000244:Adenosine Diphosphate / Q000097:blood*; D000255:Adenosine Triphosphate / Q000097:blood*; D000818:Animals; D001081:Apyrase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008297:Male; D010649:Phenylalanine / Q000378:metabolism*; D010667:Phenylpyruvic Acids / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D010667:Phenylpyruvic Acids; D010649:Phenylalanine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001081:Apyrase; C031606:phenylpyruvic acid