Inhibition of prolyl 4-hydroxylase by oxalyl amino acid derivatives in vitro, in isolated microsomes and in embryonic chicken tissues

• Published in: Biochemical journal Vol. 300; no. 2; pp. 525 - 530
• Main Authors: BAADER, E, TSCHANK, G, BARINGHAUS, K.-H, BURGHARD, H, GÜNZLER, V
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 01.06.1994
• Subjects: Amino Acid Sequence; Amino Acids - chemistry; Amino Acids - pharmacology; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Chick Embryo; Culture Techniques; Densitometry; Electrophoresis, Polyacrylamide Gel; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydroxyproline - biosynthesis; Microsomes - enzymology; Molecular Sequence Data; Oxalates - chemistry; Oxalates - pharmacology; Oxidoreductases; Procollagen-Proline Dioxygenase - antagonists & inhibitors; Procollagen-Proline Dioxygenase - isolation & purification; Spectrometry, Fluorescence; Vertebrata; Enzyme; Aminoacid; Enzyme inhibitor; Chicken; Oxidoreductases; Aves; Microsome; Mechanism of action; In vitro; Procollagen-proline dioxygenase; Biological activity
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj3000525

The potency of oxalyl amino acid derivatives as inhibitors of prolyl 4-hydroxylase was studied in vitro, in isolated microsomes and in chicken embryonic-tissue culture. These compounds represent structural analogues of 2-oxoglutarate in which the -CH2- moiety at C-3 is replaced by -NH-, with or without further structural modifications. The most efficient inhibitor of purified prolyl 4-hydroxylase was oxalylglycine. Its mode of inhibition was competitive with respect to 2-oxoglutarate. The Ki value varied between 1.9 and 7.8 microM, depending on the variable substrate used. Oxalylalanine inhibited purified enzyme with a Ki of 40 microM. Other oxalyl amino acid derivatives showed little inhibitory activity. In microsomes isolated from embryonic chicken bone, oxalylglycine and oxalylalanine inhibited prolyl hydroxylation with IC50 values of 23 and 120 microM respectively. Dimethyloxalylglycine was not an inhibitor of purified prolyl 4-hydroxylase and only weakly active in the microsomal system, but efficiently suppressed hydroxyproline synthesis in embryonic chicken calvaria and lung. The data suggest that dimethyloxalyl amino acids are converted into active inhibitors in intact cells, most likely in the cytoplasmic compartment.