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Characterization of the aminopeptidase activity of epidermal leukotriene A 4 hydrolase against the opioid dynorphin fragment 1–7
Author(s) -
NISSEN J.B.,
IVERSEN L.,
KRAGBALLE K.
Publication year - 1995
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.1995.tb02749.x
Subject(s) - chemistry , aminopeptidase , dynorphin , biochemistry , hydrolase , opioid peptide , phosphofructokinase 2 , enzyme , stereochemistry , amino acid , receptor , opioid , leucine
Summary Leukotriene A 4 hydrolase is a bifunctional cytosolic enzyme, which both hydrolyses leukotriene A 4 (LTA 4 ) into leukolriene B 4 (LTB 4 ) and exerts aminopeptidase activity against opioid peptides. In the present study we have investigated whether the peptides angiotensin I and II. bradykinin, kallidine. histamine, dynorphin fragment 1–7 and substance P can act as substrates for epidermal and neutrophil LTA 4 hydrolase. Among the tested substrates, dynorphin fragment 1–7 was found to be the best substrate for the enzyme. The aminopeptidase activity of epidermal and neutrophil LTA 4 hydrolase against dynorphin fragment 1–7 was further characterized. The enzyme was purified from human epidermis and human neutrophils by anion exchange chromalography (Q‐Sepharose) and affinity chromatography on a column with the LTA 4 hydrolase inhibitor bestatin coupled to AH‐Sepharose. The incubation of the dynorphin fragment 1–7 with LTA 4 hydrolase resulted in the formation of tyrosine. The presence of the N‐terminal amino acid tyrosine is essential for the interaction of opioids with their receptors, and this finding indicates that the LTA 4 hydrolase can inactivate dynorphin fragment 1–7. After the two purification steps no other aminopeptidases acting at the N‐tetminal tyrosine of dynorphin fragment 1–7 was present in the preparation. This was demonstrated by the abolishment of the degradation at the N‐terminal end of dynorphin fragment 1–7 when preincubaling the enzyme preparation with LTA 4 before the incubation with the dynorphin fragment 1–7. The abolishment of the aminopeptidase activity shows that activation of the hydrolase part of the enzyme, with conversion of LTA 4 into the potent proinflammatory compound LTB 4 , results in an inhibition of the aminopeptidase activity of the enzyme. As a result, the catabolism of dynorphin fragment 1–7 and probably of other opioid peptides is inhibited, resulting in sustained biological effects of these opioids. This phenomenon may be important for the maintenance of inflammation in skin conditions, such as psoriasis and atopic dermatitis, in which LTB 4 is formed.