The effect of N-terminal acetylation and the inhibition activity of acetylated enkephalins on the aminopeptidase M-catalyzed hydrolysis of enkephalins.
High performance liquid chromatography and high performance liquid chromatography/electrospray ionization-mass spectrometry were used to study the effect of N-terminal acetylation and the inhibition activity of acetylated enkephalins on the aminopeptidase M (EC 3.4.11.2)-catalyzed hydrolysis of methionine (Met-enk) and leucine enkephalins (Leu-enk). Acetylation imparts a significant enhancement in the proteolytic stability of these two peptides. After 30 min of the reaction, < 10% of both acetylated enkephalins was hydrolyzed. In an 8-h incubation period, only a maximum of 54% acetylated (Ac)-Met-enk and 38% Ac-Leu-enk was hydrolyzed. Vmax and Km [infil] for the degradation of Ac-Met-enk were 1.4 nmol/min/50 ng and 2.2 mM, respectively. The corresponding values for the reaction of Ac-Leu-enk were 0.5 nmol/min/50 ng and 0.9 mM. Also, the aminopeptidase M activity on Met-enk can be inhibited in the presence of Ac-Met-enk, which acts as a mixed-type inhibitor with the inhibition constant (K(i)) of I x 10(-3) M.
Jayawardene
D S
DS
Department of Chemistry, University of Memphis, TN 38152, USA.
Dass
C
C
D000107:Acetylation; D000626:Aminopeptidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002384:Catalysis; D004745:Enkephalins / Q000737:chemistry* / Q000494:pharmacology*; D006868:Hydrolysis; D063208:Methionyl Aminopeptidases; D013329:Structure-Activity Relationship
D004745:Enkephalins; D000626:Aminopeptidases; D063208:Methionyl Aminopeptidases