Abstract
Bestatin, an inhibitor of aminopeptidases, was also a potent inhibitor of leukotriene (LT) A4 hydrolase. On isolated enzyme its effects were immediate and reversible with a Ki = 201 +/- 95 mM. With erythrocytes it inhibited LTB4 formation greater than 90% within 10 min; with neutrophils it inhibited LTB4 formation by only 10% during the same period, increasing to 40% in 2 h. Bestatin inhibited LTA4 hydrolase selectively; neither 5-lipoxygenase nor 15-lipoxygenase activity in neutrophil lysates was affected. Purified LTA4 hydrolase exhibited an intrinsic aminopeptidase activity, hydrolyzing L-lysine-p-nitroanilide and L-leucine-beta-naphthylamide with apparent Km = 156 microM and 70 microM and Vmax = 50 and 215 nmol/min/mg, respectively. Both LTA4 and bestatin suppressed the intrinsic aminopeptidase activity of LTA4 hydrolase with apparent Ki values of 5.3 microM and 172 nM, respectively. Other metallohydrolase inhibitors tested did not reduce LTA4 hydrolase/aminopeptidase activity, with one exception; captopril, an inhibitor of angiotensin-converting enzyme, was as effective as bestatin. The results demonstrate a functional resemblance between LTA4 hydrolase and certain metallohydrolases, consistent with a molecular resemblance at their putative Zn2(+)-binding sites. The availability of a reversible, chemically stable inhibitor of LTA4 hydrolase may facilitate investigations on the role of LTB4 in inflammation, particularly the process termed transcellular biosynthesis.
Highlights
Pharmacological restraint of LTB, formation may alleviate some inflammatory symptoms, complementing the action of agents which inhibit formation of prostaglandins [7]
We report that LTA, hydrolase contains an intrinsic aminopeptidase activity and that bestatin, an amiinhibited LTB, formation >SO%within 10 min; with nopeptidase inhibitor, inhibitsLTA, hydrolase
The results demonstrate a functional resemblance between LTA4 hy
Summary
PurifiedLTA, hydrolase Materials-LTA, methyl ester, LTB,, and prostaglandin B,were exhibited an intrinsic aminopeptidase activity, hydro- from Cayman Co.B; SA, bestatin ((2S,3R)-3-amino-2-hydroxy-4lyzing L-lysine-p-nitroanilide and L-leucine-@-na- phenylbutanoyl-L-leucine),amastatin ((2S,3R)-3-amino-2-hydroxyphthylamide with apparent K,,, = 156 p~ and 70 p~ 5-methylhexanoyl-~-valine-~-valine-~-aspartaiccid), epibestatin and V,,, = 5 0 and 215 nmol/min/mg, respectively. Both LTA4 and bestatin suppressed the intrinsic aminopeptidase activity of LTA, hydrolase with apparent Ki values of 5.3 p~ and 172 nM, respectively. LTA, Hydrolase Is Functionally Related toan Aminopeptidase mined by incubating lysed neutrophils with 70 FM bestatin and 100 p~ arachidonic acid or 10 PM LTA,for 10min.Samples were quenched, extracted, and analyzefodr 5-HETE, 15-HETE, anLdTB,. Intrinsic aminopeptidase activity of LTA, hydrolase, purified to homogeneity, was monitored by incubating enzyme(14Fg/ml) in 0.010 M Tris, pH 8, containing 1 mg/ml BSA, with 0.10-1 mM Llysine p-nitroanilide. Comparatiue evaluation of metallohydrolase inhibitors as inhibitors of LTA, hydrolase inhibition Compound
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
